Usenet and the access to Usenet is completely legal. Usenet is comparable with the Internet and serves for exchanging information in a legit way. Similar to the Internet, Usenet offers the opportunity for downloads. The question about legality comes predominantly in combination with the usage of newsgroups from the sub-hierarchy alt.binaries, which was cut out to be specialized for spreading binary data attachments.
The usage of Usenet, consisting of subscribing to newsgroups, reading or commenting of postings plus communication, in the case of no slanderous content or human rights violations, is entirely legal. Even downloading files is in most cases permissible, as long as the movies, programs or files are unrestrictedly available and don’t cause any conflicts with copyright law. Consequently complications can merely occur in binary-newsgroups, because all sorts of file attachments are allowed here. If the author of the posting isn’t the originator of the provided data, the author acted illegal. The poster violated the law of copyright and can be liable to prosecution. But contrary to P2P-filesharing, using a premium-account of Usenet is entirely anonymous, due to SSL encrypted connections and closed lines.
Eventually misconduct of a few individuals users leads to the connection of the terms illegality and Usenet. If you want to use Usenet only with the intention of reading and commenting posts, or as a tool of communication, you can do this without compunction. Not legal is solely the download of scattered files protected by copyright law – but Usenet by itself is completely legitimate and licit.