SAO PAULO (AP) Police in Brazil are starting to employ a dictatorship-era national security law against critics of President Jair Bolsonaro, while lawyers and activists rally to provide them with legal help and accuse the government of trying to silence dissent.

On Friday, demonstrators challenged police in the capital by parading with anti-Bolsonaro signs a day after four protesters were detained. They had called the president genocidal for his handling of the coronavirus pandemic and displayed a cartoon depicting him next to a Nazi swastika. Officers took no action Friday as about 40 people protested for an hour.

The national security law, which dates from 1983, near the end of the countrys military dictatorship, makes it a crime to harm the heads of the three branches of government or expose them to danger. The vague measure has recently been used to detain or investigate Bolsonaro critics.