Trump threatens to impose Insurrection Act amid Minnesota protests – what is the law about, how was it used?

US President Donald Trump has warned on Thursday, 15 January, that he would impose the Insurrection Act if people in Minnesota fail to comply with the law and attack federal agents.

"If the corrupt politicians of Minnesota don’t obey the law and stop the professional agitators and insurrectionists from attacking the Patriots of I.C.E., who are only trying to do their job, I will institute the INSURRECTION ACT, which many Presidents have done before me, and quickly put an end to the travesty that is taking place in that once great State," Trump wrote on Truth Social.

Tensions escalated in the region, where demonstrators condemned the killing of 37-year-old Renee Nicole Good last week. The Trump administration has intensified immigration enforcement in the city and deployed thousands of agents to arrest people.

A Venezuelan man was shot and injured by a federal immigration agent on Wednesday, authorities said, Wall Street Journal reported. According to the Department of Homeland Security, the officer shot the man in the leg after he tried to escape, it added.

Federal military forces are typically not authorised to carry out civilian law enforcement duties against US citizens, except in times of emergency. The law authorises troops to engage in domestic law enforcement actions like making arrests and conducting searches, which they are normally restricted from performing, the Guardian reported.

The law serves as an exception to the Posse Comitatus Act, which generally imposes strict limitations on the use of federal forces within the country. Any invocation of the Insurrection Act would likely encounter legal challenges, according to a report by Harvard Kennedy School (HBS).