The legal certainty principle is the main foundation in the modern legal system, including in the context of e-commerce transactions that are currently experiencing rapid development. In the digital trade era, legal certainty has a crucial role in giving guarantees to business owners and consumers so that they may conduct transactions safely without being haunted by uncertain regulations or threats of legal sanctions.

The application of this principle in the scope of e-commerce still faces rather complex challenges. Even though there are already regulations such as the Law on Electronic Information and Transaction as well as the Law on Consumer Protection, the implementation of these regulations is still unable to answer all the dynamics of interstate and interjurisdictional digital transactions. One of the forms of legal response towards the norm void is reflected in the Decision of the Supreme Court No. 1305/B/PK/PJK/2015 which becomes an important pillar in the resolution of taxation disputes in e-commerce activities. In this decision, the Supreme Court firmly states that digital transactions still have legal consequences that are equal to those of conventional transactions, especially in the case of taxation obligations. Judges state that even though transactions are carried out online, it does not mean that they are free from applicable legal regulations, including taxation obligations. The approach that the Supreme Court took shows efforts to bridge the regulatory void through a progressive and contextual interpretation, adapting to technological developments as well as the need for legal certainty in the digital society.

In this context, the legal certainty principle is translated as a clarity of norms; consistency in applying regulations; and jurisdictive clarity, especially regarding who has the obligation to pay tax; the legal basis for tax imposition; and the Indonesian authority in imposing tax on digital businesses. In making the decision, the Supreme Court utilized the jurisprudential approach to interpret taxation regulations that have not explicitly regulated interstate digital transactions. This approach is important as there are not yet any comprehensive and operational positive regulations in accommodating the complexity of global e-commerce.

One of the significant contributions of that decision is the acknowledgement towards the importance of flexibility in contextually interpreting laws, considering that many Subadriyah & Arum Widiastuti transactions involve foreign servers or parties. This decision also firmly states that electronic transactions are not exempted from taxation obligations and the state still has the right to impose tax on economic activities that occur in Indonesia's jurisdiction, even if the medium has digital characteristics. Even so, the Supreme Court realizes that domestic regulations still have limitations in facing the global reality, such as the issue of servers located in foreign countries; identification of foreign tax subjects; as well as challenges in reaching digital tax objects in an accurate and effective manner.

When compared to international legal standards, such as the UNECIC and the WTO policy frameworks, it can be seen that the Indonesian legal system still needs to be improved to achieve better harmonization. International standards have priorly regulated principles on the validity of electronic documents, the acknowledgement of digital signatures, personal data protection, and the jurisdiction of interstate transactions. This Decision of the Supreme Court opens a room for reflection on the need to renew the national law, making it more inclusive towards those principles. Regarding legal certainty, business owners need clarity and certainty on the legal obligations that they must fulfill related to taxation matters, consumer protection, as well as applicable procedures to resolve disputes. This decision contributes to strengthening the rights and obligations of e-commerce actors in Indonesia as well as placing the Supreme Court as an institution that has a corrective role in filling the legislative void or inadequacy. Jurisprudence in this case not only functions to complement the law but is also a crucial guideline in the practice of justice and policy formulation.

The strengthening of the legal certainty principle through this decision also impacts the increase in digital business actors' trust to operate in a manner that complies with regulations. In the long term, this will strengthen Indonesia's digital economic structure, making it more inclusive and competitive. Through this decision, the Supreme Court also shows the justice institution's adaptability in responding to the complexity of digital transformation. The acknowledgement of electronic evidence in the context of taxation disputes shows the availability of the legal system to transform in line with technological advancement. This simultaneously strengthens the legitimacy of digital pieces of evidence in the legal evidencing process.

Further, in this context, the legal certainty principle is not only sourced from laws but also from judicial decisions that reflect the principles of justice, relevance, and impartiality to the dynamics that currently occur in society. This decision also reminds the government of the urgency to systematically renew regulations. Mere jurisprudence is not enough to answer all legal problems in e-commerce without the support of clear and updated regulations.

The Decision of the Supreme Court No. 1305/B/PK/PJK/2015 has a strategic meaning as an initial point in developing a national e-commerce legal system that is adaptive, integrated, and responsive towards global challenges. With the support of legal harmonization and institutional strengthening, it is hoped that Indonesia may be able to create a digital trade ecosystem that guarantees legal certainty as well as encourages sustainable technology-based economic innovations.

In e-commerce transactions in Indonesia, the legal certainty principle is one of the important aspects that support the trust and continuity of digital trade (Moho, 2019). Legal certainty refers to the clarity of regulations that govern transactions in the digital world, encompassing the rights and obligations of consumers and business actors (Remaja, 2014). In Indonesia, even though there are already regulations such as the Law on Electronic Information and Transaction as well as the Law on Consumer Protection, there are still challenges to the implementation and monitoring of these regulations (Julyano & Sulistyawan, 2019). Unclear jurisdiction as well as legal stipulations that are not fully in line with technological advancement and global dynamics often become hindrances for business owners and consumers in carrying out transactions comfortably and securely (Barkatullah, 2019).

In line with the increase in interstate e-commerce transactions, the need to align domestic regulations and international standards becomes increasingly crucial (Kapoh, 2020). International agreements such as TRIPS (Trade-Related Aspects of Intellectual Property Rights) and regulations from the WTO provide a basic framework that can strengthen legal protection in digital transactions without the existence of an alignment between domestic and international regulations. The Indonesian legal system will face difficulties regulating and resolving e-commerce disputes, especially in cases involving foreign parties. Therefore, the strengthening of regulations and the creation of more adaptive dispute resolution mechanisms become the key to achieving optimum legal certainty in the digital trade era.

The Decision of the Supreme Court No. 1305/B/PK/PJK/2015 is one of the examples of an important precedent in resolving tax disputes related to e-commerce transactions in Indonesia. This case emerged as a response towards the development of technologies and digital trade that becomes increasingly complex. In its Decision, the Supreme Court firmly states that e-commerce activities have the same legal consequences as conventional transactions, especially regarding taxation obligations even though it is digital-based.

The legal consideration in this decision emphasizes the importance of enforcing justice for all of the parties involved (Khafifi, XXXX). Judges make efforts to make sure that the state's interests in regulating and imposing taxes on e-commerce transactions may be accommodated without ignoring the rights of business owners (Ayu, 2018). Judges consider the legal certainty principle as the main basis in deciding upon that case. This case is crucial to create business owners' sense of confidence in the e-commerce sector as well as to protect the rights of citizens in collecting tax according to legal regulations.

Even so, this decision also uncovers the limitation of the national regulation in facing the dynamics of interstate digital trade. One of the main issues discussed regards the location of the server and transactional jurisdiction that often becomes a topic of debate in the imposition of e-commerce tax (Maxuel & Primastiwi, 2021). In the Indonesian legal system, there are no regulations that specifically regulate how servers located overseas or transactions involving foreign parties may be imposed with tax. Domestic regulations have not yet fully answered global challenges that come with electronic trade.

Apart from that, this decision also reflects the need to develop regulations that are more adaptive to technologies and globalization (Makalalag, 2016). The Indonesian legal system still faces challenges in integrating international principles that have been adopted into various advanced countries, such as the protection of digital consumers' data as well as the mechanism of interstate dispute resolution. Therefore, the Decision of the Supreme Court No. 1305/B/PK/PJK/2015 becomes a reminder of the importance of legal reformation that not only focuses on the domestic aspect but is also able to synergize with global standards for the creation of a sustainable and just e-commerce ecosystem. To answer these challenges, international agreement policies related to e-commerce, such as UNECIC as well as initiatives from the WTO become examples of how regulations can be designed in a harmonious and comprehensive manner to accommodate the dynamics of global electronic trade.

International agreement policies related to e-commerce, such as UNECIC as well as initiatives from the WTO show the seriousness of global efforts in creating a harmonious and comprehensive regulatory framework (Tarigan et al., 2024). Electronic trade requires clear regulations so that business owners, consumers, and the government may efficiently carry out their roles (Budi, 2018). UNECIC, for instance, focuses on the use of electronic communication in international contracts offering legal certainty on the validity of electronic transactions and more efficient evidencing mechanisms (Sukarno et al., 2022). This simultaneously creates an environment that supports the growth of e-commerce at the global level.

One of the important aspects that is regulated in this international policy is data security. In the digital era, personal data and transaction information have become highly valuable assets (Prayuti, 2024). Data protection becomes the main priority in the international legal framework. International agreements such as the GDPR (General Data Protection Regulation) which was adopted by the European Union give an example of concrete steps to regulate individual rights related to their personal data. This regulation also governs how data can be transferred between countries by guaranteeing the same standard of protection, preventing misuse and making sure that consumers' privacy rights are protected.

Consumer protection also becomes the main attention in international e-commerce policies (Firmansyah, 2017). With the increasing number of transactions that are carried out online, the risks that consumers face also increase, such as fraud or products that are different from what was offered (Bengu et al., 2024). International policies such as guidelines from the WTO and other initiatives strive to give a stronger protection mechanism for consumers all over the world. This encompasses the transparency of product information, the rights to return goods, as well as giving compensation in case sellers violate contracts (Widiarty, 2024). It is hoped that the existence of these regulations may increase consumers' trust in making transactions in the global electronic market. International policies offer a more structured policy in handling disputes involving parties from various countries (Lumentut, 2021). UNECIC, for instance, facilitiates electronic dispute resolution by providing clear procedures on how disputes may be resolved in court or through international arbitrages (Lawra & Mulyeni, 2022). Apart from that, WTO also promotes a transparent and efficient dispute resolution system to make sure that the occurring disputes may justly be resolved without harming one of the parties.

Just taxation is a crucial topic in the international policy framework on e-commerce (Isal & Sidik, 2023). One of the main challenges in taxing e-commerce is determining which country has the right to impose taxes that occur online, especially in transactions which involve business owners and consumers from various countries. International initiatives, such as those discussed in WTO forums make efforts to create a taxation system that not only prevents tax evasion but also creates conditions where no country is harmed (Rohendi, 2015). International agreements on tax over digital services and goods that are traded through electronic means provide guidelines on how tax must be applied in a just and balanced manner considering the characteristics of global e-commerce.

In line with global efforts to create a just taxation system, the Decision of the Supreme Court No. 1305/B/PK/PJK/2015 becomes a crucial point in describing how the Indonesian legal system responds to the quick development of global e-commerce in the domestic context. While international policies focus on the creation of a balanced taxation system that does not harm any country, this case shows the reality that the existing regulations in Indonesia are not yet fully adequate in facing the challenges that occur in interstate transactions. With the existence of e-commerce transactions that involve business owners and consumers from various locations, the misalignment between domestic regulations and the global dynamics becomes even more apparent, creating a gap in the correct and just tax imposition.

The Decision of the Supreme Court No. 1305/B/PK/PJK/2015 discusses tax disputes in interstate e-commerce transactions. These disputes occur because the e-commerce transactions carried out by taxpayers in an area and consumers in another area lead to a lack of clarity in the application of taxation regulations that were so far designed for conventional transactions. More specifically, dispute objects encompass the determination of tax obligations for interstate e-commerce transactions, the application and interpretation of taxation regulations that have not explicitly regulated e-commerce activities, as well as legal certainty on tax imposition in digital transactions that have different characteristics compared to traditional transactions. Therefore, this dispute focuses on how the national taxation system may accommodate and adapt regulations in facing challenges in interregional and cross-border electronic transactions.

In its legal development, judges assess that the current national taxation regulations are not yet fully adequate in regulating interregional e-commerce transactions and have special characteristics that are different from conventional transactions. Judges firmly state the need for adaptive and contextual legal interpretation to enforce the principles of legal certainty and justice as well as encourage the quick development of the digital economy. Judges also consider the importance of referring to international legal developments as well as international agreements that regulate electronic trade as guidelines to fill in the void in the national law. This decision states that even though taxpayers must fulfill their taxation obligations, the application of taxation regulations must be flexible and relevant with technological advancement to avoid the occurrence of a lack of legal certainty as well as hindrances for digital economic innovations.

One of the aspects that is not explicitly regulated in the taxation regulations in Indonesia is the issue of server and jurisdiction location. E-commerce transactions may involve parties from various countries, servers, or digital service provider data storage locations that are located outside of Indonesia. This may lead to a lack of certainty regarding the country that has jurisdictions in regulating that transaction, especially related to taxation obligations. For instance, in the case of transactions between consumers in Indonesia and service providers with a basis located in another country, there are no clear stipulations on whether or not Indonesia has the right to impose tax. This leads to a lack of legal certainty that may potentially bring harm to a country in the case of tax collection as well as hinder the development of the domestic e-commerce sector (Subagijo & Lie, 2024).

Aside from the issue of jurisdiction, another challenge that the Indonesian legal system faces is the gap in regulations on consumer data protection. In e-commerce, information, consumers' personal data often becomes one of the most valuable assets. It is unfortunate that the law that applies in Indonesia, especially those related to personal data protection is still limited. Even though Indonesia has enacted the Law on Personal Data Protection in 2023, this law is still at the implementation level and has not encompassed all the needed aspects to regulate e-commerce transactions that involve the data of international consumers. Even though the Law on Personal Data Protection has been applied as a legal basis to regulate data security, its implementation still faces challenges. The cases of personal data leakage and the misuse of sensitive information still often occur (Fathur, 2020). Meanwhile, the law enforcement based on the Law on Personal Data Protection has not shown that there are significant examples of perpetrators who are imposed with severe punishments (Mirnayanti, 2023). This may potentially weaken consumer trust and hinder the Subadriyah & Arum Widiastuti development of the e-commerce sector which highly depends on data protection guarantees (Putri et al., 2025).

The incapability of the Indonesian legal system in handling interstate issues also creates hindrances in resolving e-commerce disputes. In many cases, the parties involved in e-commerce transactions may be in different countries, making the dispute resolution process difficult. Even though Indonesia has the Law on Arbitrage that allows dispute resolution through alternative means, the resolution of international disputes often faces issues of decision implementation and acknowledgement, especially when involving countries that do not have bilateral agreements on arbitration. This indicates that Indonesia needs to strengthen its interstate dispute resolution mechanism according to international standards to support the increasingly complex development of e-commerce (Wijaya, 2022).

In the context of e-commerce, the legal reality in Indonesia shows a disalignment between existing domestic regulations and the challenges faced by interstate electronic trade. To respond to global developments and increase competitiveness, Indonesia needs to carry out a more profound legal reformation, including adapting regulations on tax and data protection as well as strengthening the dispute resolution mechanism. This will also make sure that Indonesia can synergize with international policies related to electronic trade as reflected in international agreements that have been signed by many countries (Kristiawanto, 2022).

The Indonesian legal system faces a series of significant challenges in regulating interstate e-commerce transactions which are mostly related to differences in regulations and jurisdictive ambiguity (Lase, 2024). E-commerce transactions often involve parties from different countries with varying legal systems. This makes it very difficult to create a consistent and just legal implication especially in the case of dispute resolution (Sukarno et al., 2022). There is a lack of clarity on jurisdiction, i.e., which country has the authority to resolve issues that occur from such transactions often hinder an effective law and an efficient process (Ramadhani et al., 2022). Apart from that, varied regulations from various countries regarding consumer protection, intellectual property rights, and data privacy increase the complexity in regulating interstate e-commerce.

Another challenge regards monitoring and implementation of domestic regulations that have not fully answered the dynamics of global e-commerce (Paryadi, 2018). Even though Indonesia already has regulations such as the Law on Electronic Information and Transaction as well as the Law on Consumer Protection. These two regulations have not fully encompassed the rapid development of e-commerce and digital technologies (Effendi, 2020). There are many digital transactions involving international digital platforms that have not been fully encompassed in Indonesian law. This leaves a gap that may be utilized by business owners or consumers to avoid the existing stipulations, such as the violation of intellectual property rights or fraud in transactions (Aprilia, 2014).

Another challenge is the incapability of the Indonesian legal system in adapting to applicable international agreements on e-commerce (Cicierdis, 2016). International agreements such as TRIPS (Trade-Related Aspects of Intellectual Property Rights) and the regulations determined by the World Trade Organization (WTO) have an important role in determining global standards for digital transactions (Sengge & Umar, 2024). However, Indonesia still faces a gap in aligning its domestic regulations with these global standards. Without an alignment between domestic regulations and international agreements, the Indonesian legal system will face challenges in overcoming the issues that occur from interstate e-commerce transactions, such as intellectual property rights, personal data protection, and the resolution of international disputes (Kennedy & Wartoyo, 2024).

Therefore, to answer the challenges faced by e-commerce in Indonesia, there needs to be concrete steps that encompass a more adaptive regulatory reformation. Indonesia must renew its legal system so that it is in line with global development, as reflected in international policies related to e-commerce. It is important for Indonesia to integrate with globally accepted international principles as reflected in international agreements such as UNECIC. For instance, UNECIC provides clear guidelines on electronic transactions and digital documents that may be used as a reference for Indonesia in arranging regulations that are more comprehensive and responsive towards cross-border needs of digital trade.

The ideality of e-commerce regulations in the global context may be seen from international policy efforts such as the UNECIC (United Nations Convention on the Use of Electronic Communications in International Contracts) which offers legal principles that are more adaptive to technological development and the dynamics of digital trade. UNECIC offers a clear definition of electronic transactions as well as defines the legal criteria that Subadriyah & Arum Widiastuti apply to electronic documents, encompassing the validity aspect and its acknowledgement in international transactions. Electronic trade is crucial as cross-border contracts often involve various documents and digital communication that need to be regulated by clear and standardized laws.

Apart from that, United Nations Convention on the Use of Electronic Communications in International Contracts (UNECIC) also regulates the acknowledgement and acceptance of electronic signatures that are an important element in e-commerce transactions. The principles that UNECIC brings provide legal certainty for the parties that are involved in interstate transactions, including consumers, business owners, as well as state institutions. By acknowledging electronic signatures and digital documents, UNECIC helps create a system that facilitates the growth of a secure and valid digital trade, decreasing the legal obstacles between countries with different legal systems (Nations, 2006).

Another international initiative that also plays a crucial role in forming e-commerce regulations is the World Trade Organization (WTO). The WTO emphasizes the importance of interstate cooperation in regulating electronic trade, especially in the case of taxation and the resolution of international disputes. In line with the increase in online trade of goods and services, WTO strives to create a system that encourages transparency, justice, and stability in global e-commerce transactions. One of the issues that is discussed in WTO forums is the taxation of digital transactions, including efforts to prevent tax evasion and ensuring that all parties justly pay their tax according to their obligations (Organization, 2021).

A just taxation system becomes the main issue discussed in the WTO, considering the cross-border characteristics of e-commerce. Every country has different taxation regulations which may lead to a lack of legal certainty and chances to evade tax, especially in interstate transactions. Therefore, the WTO principles strive to guarantee that global e-commerce transactions are not only regarding the issue of taxation but also create an agreement between states regarding fiscal obligations that must be fulfilled. This policy focuses on creating justice in taxation and making sure that no country is harmed due to an imbalance in the existing taxation regulations (Organisation for Economic Co-operation and Development (OECD, 2020).

Ideally, e-commerce regulations not only regulate electronic transactions but must also have the capability to answer global challenges that emerge in the digital era. UNECIC and WTO initiatives show the urgent need for a harmonization of international law that may regulate the global technical and practical aspects of e-commerce. By adopting principles that are more adaptive towards technological advancement, this international regulation plays a crucial role in creating a legal order that supports the growth of a just, transparent, and sustainable digital economic growth all over the world (Widijowati, 2023).

When comparing Indonesian national regulations and international policies, this study found a significant gap. Even though Indonesian regulations have governed tax on e-commerce, it has not encompassed more extensive aspects such as data security and digital consumer protection. On the contrary, international policies have accommodated these principles, creating a more comprehensive legal framework. This gap can also be seen in the law enforcement practice as reflected in the Decision of the Supreme Court No. 1305/B/PK/PJK/2015. This decision has succeeded in applying the existing domestic regulations but still has not referred to international standards, making Indonesian regulations less relevant in facing the increasingly complex interstate e-commerce transactions (Fista et al., 2023).

The lack of referential international policies in this decision shows that Indonesian domestic regulations are not yet adequate in facing e-commerce global challenges that involve various jurisdictions. Without understanding and adopting international regulations, Indonesia risks experiencing legal uncertainty and hindering the growth of national e-commerce. Therefore, it is crucial to carry out a legal reformation that accommodates international standards, including UNECIC principles and WTO recommendations, so that the domestic regulations may be aligned with the dynamics of global trade and provide adequate legal protection for business owners and consumers in Indonesia (Alif, 2008).

This research offers a scientific contribution in identifying the strengths and weaknesses of e-commerce regulations both at the national and international levels, as well as offering a practical recommendation to strengthen the e-commerce legal system in Indonesia. This research substantially confirms the importance of a legal harmonization between domestic regulations and international standards to encourage a sustainable digital economic growth. Another crucial contribution is an emphasis on the urgency of the development of e-commerce regulations that are adaptive towards technological dynamics and are able to accommodate global principles such as data protection, taxation justice, as well as the resolution of interstate disputes.

The policy implications from this research encompass the need for a revision towards regulations on digital taxation, the strengthening of a digital-based consumer protection framework, as well as the formation of a dispute resolution mechanism that is compatible with technological development and global contexts. Therefore, the results of this research may become a strategic reference for stakeholders, including policymakers, academicians, as well as industrial actors in creating an e-commerce legal system that is more responsive and inclusive as well as one which has international-standard competitiveness (Nugroho, 2021).