Shaneen Allen's rise from single Philadelphia mom to global gun rights icon has the elements of a John Grisham thriller: violent crime, race, and the power of the state over the individual.

An African-American, Ms. Allen was arrested in 2012 after a traffic stop in New Jersey. She faced up to five years in prison under New Jersey law – not for lacking a concealed-carry permit for her firearm, but for having the wrong one.

A bill passed in the US House in December and now up for consideration in the Senate would force all states to abide by each other's permits, meaning that concealed-carriers such as Allen would no longer have to navigate a Rorschach-like map of regulations as they navigate the country.

It would also mean gun-wary states such as New York would be "bound by the boldest experiment" – including states that put basically no restrictions at all on concealed-carry – as South Texas School of Law professor Josh Blackman has put it.