We already have tags, and I haven't seen any questions with "United States" or "U.S." in the title.
Yet for some state-related questions, e.g. California or Texas, it's been suggested that state should be part of the title.
Doesn't this show prejudice in what the title should be in regards to US federal vs. state laws, vs. the rest of the world?
Many sites have struggled with similar questions (tags vs titles); there have been arguments on both sides. I'm a big proponent that a question (thus, the title) should be self contained and we should not rely on tags to establish context.
The counter-argument is that is becomes somewhat tedious to have every question end in "…in the United states." It turns out that we're both right.
So generally speaking, if the jurisdiction can fit naturally and it makes the question more clear, I say use it. For example, saying, "Does US Copyright law allow for..." can sound just as natural as, "Does Copyright law..." But you don't have to force it.
We should always strive to make titles clear as possible, but they should be easy to read and understand, too. Use your judgement and edit titles to be as clear as possible. They are the main signage and billboard/welcoming mat to your site.
Relevant: Should questions include “tags” in their titles? on Meta SE
