Definition of preemption
1a : the right of purchasing before others especially : one given by the government to the actual settler upon a tract of public land
b : the purchase of something under this right
2 : a prior seizure or appropriation : a taking possession before others
3a : a doctrine in law according to which federal law supersedes state law when federal law is in conflict with a state law
Even without an express provision for preemption, we have found that state law must yield to a congressional Act in at least two circumstances. — Crosby v. National Foreign Trade Council
— called also federal preemption
b : a doctrine in law according to which the legislation of a superior government (such as a state government) supersedes that of an inferior government (such as a municipal government) in conflicts of law
4 : a policy of launching a preemptive attack in order to prevent a suspected imminent attack
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Time Traveler for preemption
The first known use of preemption was in 1602
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