I can't find a clear consensus on "the jurisdiction problem." (A digest of previous meta discussion on this would be helpful here.)
Before this suggestion gets too far along I want to provide some observations:
We have many questions about law that are sufficiently general that good answers can be written without jurisdiction being specified. In most cases it would be possible to scope the Q&A: E.g., "This answer is only valid under common law." But is that helpful? E.g., many Q&A implicitly apply to united-states, and that tag is often used (presently on 2239 of our 8749 questions). But it might also be overused: Outside of constitutional questions, many answers that apply in the U.S. are valid, or at least helpful, in all common-law jurisdictions.
Granted, we do see some questions about laws that vary so broadly by jurisdiction that a "good" answer cannot be written without a jurisdiction being specified. (Note that in such cases the odds of someone having that jurisdiction-specific knowledge might be low – somewhere in previous meta discussion I recall suggesting something like, "A somewhat helpful general answer is better than no answer at all." Note also that very specific questions are often properly closed as requests for legal advice.)
Under the status quo I often see opposite problems, including:
Askers being nagged in comments to provide a jurisdiction even when jurisdiction is not necessary to provide a helpful answer.
Helpful answers for jurisdictions other than the one tagged being downvoted.
I worry about whether instructions to include jurisdiction will increase these problems and create more (avoidable) moderation noise.