This is 99% invisible. I'm Roman Mars.

The Orange County Courthouse in Santa Ana, California is a large granite and sandstone building

from the early 20th century. It has Romanesque arches out front. Inside there's a courtroom,

some uninspiring conference rooms, and elaborate wrought iron staircases.

Last year, Jennifer Birch found herself underneath it all

standing in the courthouse basement.

It was like kind of a half basement,

the little windows. It reminded me of a room that

Indiana Jones might be in or something like, you know, like it was very historical

feeling and like, okay, let's not touch anything.

The Indiana Jones style room that Jennifer stepped into

was the Orange County Historical Archives.

Jennifer was there doing research for a group called Moms Demand Action.

It's an organization that advocates for gun control and regulation.

Not all the members are actually moms.

Oh no, not at all. I work alongside men, the students.

But the thing they all have in common is that they care about gun control,

which is exactly why Jennifer was in the courthouse that day.

Moms demand action had dispatched volunteers like Jennifer to courthouse basements

and local archives all over the country to dig up some of the oldest

most overlooked gun laws in the nation's history.

And their goal, ultimately, was to fact check the highest court in the nation.

...