Ah, yes. Conflicts of Law. I had PTSD after that class! So you MUST understand if I forgot something.
Here's a decent argument against the dual sovereignty thingy, I should say 'doctrine.' It is long but here is the conclusion, with which I whole heartedly agree.
Conclusion
The dual sovereignty doctrine regarding successive state and federal
prosecutions as presently applied is repugnant to the spirit of
the constitutional protections guaranteed by the Double Jeopardy
Clause. The principle of dual sovereignty lacks foundation in the
text, history and structure of the Bill of Rights. Moreover, the policy
rationale and the precedents upon which the Court has upheld
the doctrine have been undermined.
http://ir.lawnet.fordham.edu/cgi/viewcontent.cgi?article=1961&context=ulj
So, can I hope for to get another O'Mara fix anytime soon? If so, I'll put my money on him.