First, that's a principle of the penal system, not the civil courts which would decide such matters. Second, this didn't involve any legal action at all, and was instead just as a threat, basically saying that if they went forward with the standard, they would sue companies that invested into the standard, but by that point the companies would be in a bad situation as they'd have invested tremendous resources into the codec.

The moment you make any kind of non trivial program (say 20k lines and above) you almost guaranteed violate some patent so they were probably even right with their claims.

It's very difficult to preemptively establish that something is not encumbered by a patent, which is what the group releasing the standard would have to do to make the standard adoptable.

If someone successfully claims the standard infringes their patent after it is released, it failed to accomplish the goal.

I'm pretty sure that patent contests are the fanfare of Europe (not EU or anything, Europe). Since ISO and the now-disbanded MPEG group is based in Europe... (If I remembered correctly the contesting group were mainly European and Asian companies. I forgot if Nokia opposed this.)

It was just a vague threat that MPEG decided to heed, they could have decided to ignore it too.