Yeah, here's some examples of all these fascists doing exactly that:

Soviet Union - The show trials of the 1930s were conducted with full legal apparatus: confessions, judges, verdicts. Stalin's purges operated through legally constituted troikas. Entirely "lawful" by Soviet law.

East Germany (DDR) - The Stasi's surveillance and harassment programmes were codified in law. When the wall fell, many Stasi officers genuinely argued their conduct was legal under GDR statute: a defence that West German courts largely rejected.

Castro's Cuba - Mass executions after the revolution were conducted by legally constituted revolutionary tribunals. Castro explicitly defended this on legality grounds when challenged by foreign press in 1959.

Chavez/Maduro's Venezuela - Suppression of opposition media, jailing of political opponents was consistently defended as operating within Venezuelan law, which was progressively rewritten to make it so. Classic self-referential legality.

Mao's Cultural Revolution - The revolutionary committees had legal standing. Persecution of intellectuals and landlords proceeded through formal (if kangaroo) legal processes.

You should ask the language model that output this text the definition of 'whataboutism,' and if the comment you've posted responds meaningfully to the discussion at hand.