The police have been enforcing the restrictions since Saturday evening, March 14th. According to a spokesman for the Berlin home ministry, an additional police force of 200 were on the street in Berlin for this purpose. From Sunday, according to information of Der Tagesspiegel, the administrative offices of the Berlin districts will also carry out increased checks. Anyone who violates the ban on assembly and opening commits a crime.

The basis is the so-called Infection Protection Act. Violations are punished with a prison sentence of up to five years or a fine (up to 25,000 euros). They are regulated in section 16 of the law. You can find the legal regulation here, among other things.