Lets say that tomorrow Indiana made it illegal to posses any ammunition magazine that held more than 5 rounds. Even if I refuse to take people for jail for this offense, if I sit by and allow my fellow officers to do it, I'm just as guilty as they are for taking someone constitutional rights away.
While I think low capacity mags are asinine and these laws are useless and wrong, I don't see the constitutional argument. In your hypothetical, how would you go about doing your job while still following your idea of Constitutional? Who would you stop fellow officers from enforcing said laws?