You're missing something. Regardless of the rights or wrongs of this particular situation, it's self-evident that a right to freedom on expression is not carte blanche to publish anything – you're still rightly subject to controls.

OK, there could be an argument that knowingly linking to infringing files is outside of freedom of expresssion. But the article says nothing about a knowledge criterion.

It says "owners of sites found to be making money [directly or indirectly!] from linking to pirated material will face prison sentences of up to six years and the closure of their site. ... users of these link-sharing sites will not be targeted under the new law"

This is even worse. Users who knowingly post links to infinging files would be a more appropriate target than the site owners. Under the new law, anyone who allows user posts will have to pre-moderate everything or prohibit users posting links?

The obvious problem with the law is much more basic: how can the site owner know whether there is or is not infringement at the other end of a link? Are site owners expected to somehow have a list of all copyrightable works and know the terms on which each of them is licensed to each recipient?

Placing the burden on the operator of the linking site creates a situation where no one will dare to make a link, because if it turns out to go to something infringing the linker will be subject to prosecution.

This is what I found with a quick search on the Constitute Project:

"the right to freely express and spread thoughts, ideas and opinions through words, in writing or by any other means of reproduction."

This would imply that it's not against the law to post a link to other material regardless of the legality of that material. It's exactly the same as saying "Go to X address if you want to obtain illegal drugs" and then getting arrested, charged and imprisoned for sending someone to a known dealer...

That actually has been the law in the US (not sure whether it still is). There was a case where someone lived next door to a dealer, and customers were frequently knocking on this person's door mistakenly. One time it was an undercover cop, and the resident said "wrong door, the dealer is over there", and was arrested and prosecuted.