Maryland lawmakers' effort to ban “ghost guns,” those unregistered and untraceable firearms that can be bought online without a background check, goes before a House of Delegates committee Wednesday.

Advocates from both sides are lining up to argue their cases.

There’s Grace Simonson, a senior at Magruder High in Montgomery County, who spent hours huddled in a closet when her school was locked down last month after another student was shot in a bathroom.She says she and her friends were frantically texting each other to try to figure out what was going on.

She says the rumors were flying, but they finally learned of the shooting by tracking news organization tweets. And later they found out the shooter, another student at the school, had used a ghost gun.

Now, she’s about to testify for a bill to ban those guns in Maryland. She says anybody with a credit card could get one.

“And while there's no way to prevent a person who wants a gun to get one, what we can do is make sure that the legal ways to get one make it more difficult for people under the age of 18 to possess a ghost gun,” she says.

But it’s more complicated than that, says Mark Pennak, president of the gun rights advocacy group Maryland Shall Issue.

“Because even if you banned ghost guns in Maryland, if somebody really, really wanted a ghost gun as opposed to a regular gun, all they do is go across state lines, put cash on the counter and go home with it,” he said.

As long as they aren’t federally regulated, the rules of interstate commerce would nullify anything Maryland does.

“And so all you're doing then is criminalizing law abiding owners who happen to be hobbyists,” he said.

Del. Lesley Lopez, sponsor of the House version of the bill, scoffs at that argument. She says she hears it every time a gun bill comes up.

“It's like no matter what bill you put forward, there's no amount of compromise that's respected,” she said. “Everything, you know, everything is a nail to a hammer.”

Her bill would ban buying, selling and transferring an “unfinished frame or receiver” if it does not have a serial number imprinted by a licensed manufacturer starting June 1 of this year.

After January 1, 2023, it would be illegal to own a gun without a serial number, though the ban would not apply to guns manufactured before 1968 or antique firearms. Those who own guns without serial numbers could take them to a firearms dealer to get serial numbers.

Lopez says her bill merely codifies in Maryland changes the federal Bureau of Alcohol, Tobacco and Firearms is making in its definitions.

"This bill is basically saying that you can sell those pieces,” she said, “but they have to be serialized by the manufacturer. And if you already have one of those pieces that you put together, and it’s functional as a firearm, it needs to be serialized.”

Lopez says the bill is needed because shootings with ghost guns is the fastest growing form of gun violence in the United States. She points to police records that show sharp increases in the number of ghost guns recovered annually.

“Criminals know that they can access these very cheaply, they can dispose of them very cheaply, it’s this huge loophole that criminals know exist,” she said.

But Pennak, of Maryland Shall Issue, says what the state really needs is strict enforcement of existing criminal laws, pointing to the more than 300 ghost guns the Baltimore Police Department seized last year.

“I’m willing to bet a large sum of money that every one of those guns that they seized was illegally possessed,” he said “And, thus, the possessor could have been already punished under existing state laws far more severely than any punishment meted out under this ghost gun bill.”

Grace Simonson, the Magruder High student, says she just wants a world where no one would have to worry about a student with a firearm coming into their school.

“So, having this legislation pass would mean there’s just another barrier in the way for teenagers to possess firearms,” she said.