That is one of the mechanisms that they were relying on. Anyone attending the event and relaying moves is likely in breach of contract, and at least could be thrown out of the venue. Likewise, anyone who signed up for the official feed and then shared the moves is violating the website's terms and conditions and could get their account closed. But it only takes one anonymous user to sign up and report the moves to other sites.

Not necessarily.

Person A opens the stream on their PC.

Unknown to them, Person B watches that stream through the window of Person A’s home, and broadcasts the information.

The only possible crime Person B did was invading Person A’s privacy, but Person A does not sue them.

Person A acted entirely legal, so did Person B, and you still got all the facts out.

Embargoes aren't rooted in laws, though. There's nothing stopping a news outlet from breaking embargo other than the reprecussions from the other company, like not getting news early in the future.

Edit: Wow, I need some sleep. I misread the OP, and the Wikipedia article to which I linked. I'll keep the comment up for posterity, but, yes, the company itself can put limitations in place but it's incredibly difficult to enforce.

There might be a contractual matter, but news and financial results cannot be protected under copyright or unfair competition theories. Without reading the case I imagine the "free riding" allegation is an unfair competition claim. I wrote a paper on this if you're interested in learning more: http://scholarlycommons.law.northwestern.edu/cgi/viewcontent....

I think it's just because the event itself is being broadcast on some television or streaming channel.

So you can't legally prevent someone from watching the official stream, then making a broadcast where they discuss facts that are relayed on that stream.

>The defendants E-Learning Ltd and Logical Thinking Ltd, which operate website Chess24.com, had argued in court papers that World Chess was seeking to stop websites from reporting on information already in the public domain and not protected by copyright law.

You can't publicly broadcast facts. Then say no one else has the right to rebroadcast those same facts.

"Why can't this mechanism be employed as a condition of being permitted to attend the event?"

There might be an issue of legality concerning the embargo in which case the limitation is warranted.