ˌmartial ˈlaw BrE AmE noun [uncountable]
a situation in which the army controls an area instead of the police, especially because of fighting against the government
impose/declare martial law
The government may declare martial law in response to the latest violence in the region.
In May, martial law was lifted (=ended) in most areas.
under martial law
According to press reports, the country is now under martial law.