This might be silly, but how about adding “As long as Arresting Constable is in play, Jail can be played for free from hand” on the Arresting Constable card? Thematic and we all know that the Council loves having the Jail out as well ^^
for being thematic, imo also starter spell cards could cost 0 with constable online. Who better than him can perform arrests and search warrants?
Sure, some combination of Jail, Lawful Search and Arrest being free to play if Arresting Constable is in play could make Law slightly better, without making them over the top.