Ah yes, martial law. Have you noticed the gold fringed flags at the courthouse?
Seriously. though, if you're concerned about the federal government imposing martial law, rest easy there are other things to worry about. You see a little research into the subject reveals that a few people in the federal government realized ole Abe Lincoln got a bit out of line during the Civil War, so this issue was addressed following that mess.
Some points about martial law:
1- I suggest reading Title 50 Chapter 34 which deals with National Emergencies, and you will see what the checks and balances are:
http://caselaw.lp.findlaw.com/casecode/uscodes/50/chapters/34/toc.html Unlike, unlike war the President can declare a national emergency, however Congress can shut him off at ANY time they choose, and are required by their own statute to periodically vote on whether to maintain a state of emergency declared by the President.
2- The president cannot just declare martial law anytime he chooses. You may want to read the Supreme Court decision in Milligan v. US (1866), in which the court ruled, "If, in foreign invasion or civil war, the courts are actually closed, and it is impossible to administer criminal justice according to law, then, on the theatre of active military operations, where war really prevails, there is a necessity to furnish a substitute for the civil authority, thus overthrown, to preserve the safety of the army and society; and as no power is left but the military, it is allowed to govern by martial rule until the laws can have their free course. As necessity creates the rule, so it limits its duration; for, if this government is continued after the courts are reinstated, it is a gross usurpation of power.
Martial rule can never exist where the courts are open, and in proper and unobstructed exercise of their jurisdiction. It is also confined to the locality of actual war."
http://caselaw.lp.findlaw.com/scripts/getcase.pl?navby=case&court=us&vol=71&invol=2
Anyone wonder why some people, like me, are so particular about whether we are at war or not? The above controls on martial law is one of the reasons. Congress hasn't declared war, and courts are still operating, so two of the requirements for martial law haven't been met.