Was re-reading constitution and noticed this in Amendment 14 sec 1:

No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States

This seems relevant for anti-gun laws of certain states. I've always thought the only way to challenge an unconstitutional law was to break it, get charged, and then take it all the way to SCOTUS, which is expensive and consumes the best part of a decade. But now I'm thinking that maybe, just maybe, we can challenge unconstitutional laws via WH petition - ask POTUS to declare them unconstitutional and therefore void?