Can blockchain be declared illegal?
<p>Some blockchains allow to embed arbitrary data in it.</p>
<p>What happens if someone embeds some illegal data, for example, a copyright-protected movie, or a collection of illegal pornography, inside a block?</p>
<p>Imagine, that it was found several years later. Can court declare distribution of offending block illegal, basically forcing a fork and erasing those several years of transactions from history (since that block is nessesary to validate them)? Will people who continue to use original chain (and dustribute original block with illegal data) be held liable for distribution of illegal content?</p>

<h2>It’s already is illegal</h2>
<p>At least, possession of child pornography is. It doesn’t matter if it’s a physical photo, a stand-alone file, or embedded in a larger file like a block chain.</p>
<p>In general, ignorance that you possess the material might protect the first few people to be charged. However, once it became widely known that the material was in the blockchain, that defence will not be available to anyone continuing to host it.</p>

blockchain