They also circumvent that law by having small elite squads of crusaders but they sometimes lend them to inquisition as a bribe and of course huge armed formations of Frateris Militia where the excuse is that those are barely controlled lynch mobs whipped into murderous frenzy by preachers so they don't count as "men at arms" which is by the way perfect 40k excuse because lynching half of planetary population is preferrable to not lynching half of planetary population just because grimdark.
They also circumvent that law by having small elite squads of crusaders but they sometimes lend them to inquisition as a bribe and of course huge armed formations of Frateris Militia where the excuse is that those are barely controlled lynch mobs whipped into murderous frenzy by preachers so they don't count as "men at arms" which is by the way perfect 40k excuse because lynching half of planetary population is preferrable to not lynching half of planetary population just because grimdark.