AMNA NAWAZ: The Supreme Court today, in a 7-to-2 ruling, upheld Biden era regulations on so-called ghost guns.

Those are firearms that can be put together at home with partially assembled kits, making them nearly impossible to trace.

Sales of those guns exploded after they came on to the market, and their use in gun crimes rose significantly too.

Joining us now to talk more about the significance of today's ruling is Jennifer Mascia, a senior news writer at The Trace, which covers gun violence in America.

Jennifer, welcome back to the "News Hour."

JENNIFER MASCIA, The Trace: Good to be here.

AMNA NAWAZ: So let's just start off with what this ruling means.

Can you help us understand what it does and also what it doesn't do?

JENNIFER MASCIA: In 2022, President Biden's DOJ implemented a rule requiring gun assembly kits to have serial numbers and buyers to undergo background checks, basically treating them like any other gun.

And these are parts kits that you can buy online and use to assemble a gun, sometimes in as little time as 20 minutes.

Justice Gorsuch, writing for the majority today, one of the court's conservative justices, he said that the regulation of some weapons parts and kits is allowed under the 1968 Gun Control Act, which says a weapon qualifies for regulation if it is capable of being readily converted into a gun.

So a gun group that's actually to the right of the NRA, the Firearms Policy Coalition, had sued over the rule a couple years ago, arguing that the government was overstepping by classifying these gun assembly kits as firearms.

But Justice Gorsuch ruled that some assembly kits can actually be covered.

There was some disagreement, though, about how broad or narrow this ruling is.

It sounds to me like it depends on the amount of time and energy that goes into putting together one of these guns from one of these kits.

Justice Gorsuch singled out a company called Polymer 80, which was responsible for most of these gun kit sales.

They have a buy, build, shoot kit, which contains all the necessary components to put together a gun in 20 minutes.

And he said, clearly, this qualifies.

AMNA NAWAZ: So this now means that manufacturers, they have to mark their products with serial numbers, they have to obtain licenses, they have to conduct background checks.

This was a regulation, though, as you mentioned, put into place by the Biden administration.

Is this ruling the end of it, or is this something in the way of regulation that President Trump could potentially roll back?

JENNIFER MASCIA: Well, President Trump didn't have much to say about ghost guns in his first administration, but this is really just a phenomenon that's arisen in recent years, really during the Biden presidency.

President Trump did sign an executive order pledging to review literally everything the Biden administration did on guns.

He could ask the DOJ to devise a new rule that reverses the ghost gun rule.

Notably, he hasn't addressed this rule in any executive orders yet, but we could very well wind up once again before the same Supreme Court.

AMNA NAWAZ: Jennifer, are there any other moves from this administration related to gun safety or gun access that you're anticipating down the line?

JENNIFER MASCIA: I think that nothing is off the table.

President Biden's administration made a lot of progress on guns, mostly with funding for community violence interruption organizations.

That funding may be disrupted at this point.

So I am looking specifically to see if he does address this rule.

Once again, if he does anything with this rule, it will be challenged immediately in another lawsuit, this time by a gun reform group probably, or a gun reform-minded citizen.

And we could end up in front of the same nine justices next year.

AMNA NAWAZ: All right, that is Jennifer Mascia, senior news writer at The Trace, joining us tonight.

Jennifer, thank you so much.

Appreciate your time.

JENNIFER MASCIA: Thanks for having me.