Recently, a question that sparked quite a discussion appeared in the crypto community. Ethereum developer Vlad Zamfir posted a poll on Twitter asking: if you discover that child abuse content is stored on the blockchain, would you still continue running a full node? The question sounds heavy, but the legal and technical issues behind it are indeed worth pondering.

The incident originated from a research report published by RWTH Aachen University, which found an inappropriate image of children and 274 related links on the Bitcoin blockchain. This has led many to worry whether, as a miner or node operator, participating in maintaining such a blockchain might violate laws. Especially in the United States, where Congress recently passed a bill called SESTA-FOSTA, aiming to hold internet service providers responsible for illegal content shared by users—even if they are unaware.

Zamfir’s poll results are quite interesting. Out of over 2,300 responses, only 15% said they would stop running a node if they found child abuse content. Princeton professor Arvind Narayanan also commented on Twitter, pointing out that mainstream media’s reaction to the report is somewhat superficial. He emphasized that law is not an algorithm, and intent plays a crucial role in determining legality.

But this indeed raises some ethical questions. Because blockchain is immutable, anyone can add unverified data in transactions. Aaron Wright from Cardozo Law School explained that this reflects a fundamental contradiction: it’s difficult to change the data structure of a blockchain, yet certain legal areas require the ability to delete or modify data.

Here, a technical detail needs to be understood. The child abuse content is not stored directly as JPEG images or videos on the blockchain; instead, it is embedded in transaction data as encoded links. Therefore, finding and decoding this content requires significant effort. Coin Center’s analysis points out that a blockchain is essentially a collection of random text strings; only knowing where to look allows attempts to decode them back into their original form.

From a legal perspective, most U.S. state laws only hold individuals responsible if they “knowingly” possess, produce, sell, distribute, or access child abuse material. The key word is “knowingly.” Since most Bitcoin users are unaware that such content is hidden within certain data, many believe RWTH Aachen’s report is somewhat alarmist.

Moreover, this issue is not limited to Bitcoin. Nearly all blockchains allow data to be added in transactions, so technically skilled individuals can embed similar illegal content on any open-source blockchain. Emin Gun Sirer from Cornell University explained on Twitter that ordinary encryption software generally lacks the tools to decode such content.

However, some technical solutions are being discussed. Some developers suggest that node operators could choose not to store the full content of certain transactions, only saving “hashes and side effects.” Bitcoin developer Matt Corallo mentioned that experienced developers could encrypt suspicious data or find other ways to make the content inaccessible. He said that storing such information in encrypted form could be acceptable, and simple encryption could solve the problem. But he also emphasized the need for clearer legal definitions so developers can address these issues more precisely.

One thing is clear: if a node operator or miner personally adds child abuse content, or knows that others are adding it, they have a legal obligation to report it to authorities. Although Bitcoin’s pseudonymous nature might complicate this, Wright pointed out that law enforcement agencies have ways to track it. They can identify who uploaded the content through blockchain records, similar to investigations into tax fraud or terrorist financing.

Overall, this topic reveals a tricky reality of decentralized ledgers. An immutable public ledger is indeed less suitable for storing sensitive or illegal information. But understanding the technical details, legal frameworks, and stakeholders’ positions is crucial. This isn’t a simple black-and-white issue; it involves a complex intersection of technology, law, and ethics.