President Trump on Monday suggested he might invoke the Insurrection Act if courts continue blocking his deployment of the National Guard to U.S. cities.

The 1807 law allows the federal government to send troops to quell domestic unrest without state approval.

A federal judge in Oregon temporarily blocked his planned deployment of California troops to Portland, and Illinois filed a similar lawsuit after he announced sending 300 guardsmen to Chicago.

Trump said the Act could be used if people were being killed and legal or local authorities obstructed action, granting the Guard full law enforcement powers, Axios has reported.

The last formal use of the law was by George H.W. Bush during the 1992 Los Angeles riots, with California’s consent.