Girl's mom, 10-year-old sibling were home at the time
In 1927, Congress passed a law barring the USPS from mailing concealable firearms unless they were from licensed dealers in an effort to curb crime.
Trump's Republican administration alleges the ban violates the Constitution's Second Amendment right to bear arms.
Pirro said there is evidence that buckshot from a shotgun carried by alleged White House Correspondents' Dinner attacker was "intertwined with the fiber" of a bulletproof vest worn by a Secret Service officer.
The first count of attempting to assassinate the president carries a maximum sentence of life in prison if convicted.
The Secret Service Presidential protection mission dates back to 1901; it was formalized after the assassination of President William McKinley.