[kragen]

It's even more true for patents: not only did the US not enforce foreign patents before the 01890s, it didn't enforce them after the 01890s either, and still doesn't today. Neither do any other countries. The PCT doesn't work like the Berne Convention.

[hilbert42]

Those who've signed it are supposedly bound by its framework. Alternatively, they wheel the fact out when it suits them/it's to their advantage in trade negotiations, etc.

[kragen]

Yes, and PCT compliance is actually fairly common, but its framework does not commit them to enforce foreign patents; rather the contrary.