According to Russian law, it is illegal to jail volunteer soldiers.

According to Russian law, it is illegal to jail volunteer soldiers (as distinct from conscripts) for refusing to fight in Ukraine. However, Putin is using the puppet governments of Donetsk and Luhansk, and the Wagner mercenaries, to jail hundreds of refusil soldiers and pretend that Russia isn't doing it.

Is it possible to establish in international law that Russia is responsible for crimes supposedly committed by those puppets?