It is in fact the case that the USA has federal statutes for murder and manslaughter (see here), but simply declines to redundantly prosecute cases where a state has done so (The “Petite” policy).
Since Zimmerman was not guilty of murder or manslaughter under Florida’s Stand Your Ground law, but would quite likely be guilty of manslaughter under federal law, there is no double jeopardy here. He was tried for homicide in Fla., but was not guilty under their particular SYG statute (Bricker calls it “hinky”). Their statute does not change the federal manslaughter statute, which does not keep burden of proof on the prosecution in a SYG defense, and indeed has no SYG defense.
It would be entirely proper and sane for the feds to prosecute any acquitted SYG defendants from Florida for federal manslaughter.
[del]I don’t see how it’s a civil rights case, though. Zimmerman wasn’t an officer of anything except in his own imagination, was he?[/del] Apparently hate crimes (as opposed to “I love you” crimes) are under “civil rights” law. OK, I get it now.