More than a dozen Democratic members of the U.S. Senate have fired off a letter to Attorney General Merrick Garland and ATF Director Steve Dettelbach to “encourage” them to issue new guidance to law enforcement regarding the Biden administration’s recently-imposed rules on DIY gun-making kits. According to the anti-gun Senators, led by Richard Blumethal of Connecticut, the rule, which requires kits containing unfinished frames or receivers to be treated as finished firearms (including a serial number and background checks on commercial sales), is supposedly being circumvented by companies exploiting a loophole in the rule.

Notwithstanding the Ghost Gun Rule, ghost gun companies have continued to sell the parts and tools to make these dangerous firearms—contending that the final rule fails to cover them and their products. These companies have adopted the position that selling nearly-complete frames and receivers without the tools (commonly known as jigs) or instructions to complete them means that their products are not firearms under federal law. Of the 100 companies previously known to sell unserialized and nearly-complete frames and receivers, dozens remain engaged in that business—including selling nearly-complete unserialized frames and receivers as well as offering the standalone tools and equipment with directions to help purchasers complete them.

The final rule, however, is clear and unambiguous: a nearly-complete frame or receiver is a firearm. The rule does not cover only frames and receivers sold as part of a kit, but also frames and receivers that can be readily completed. Indeed, enforcing the rule only against sellers of kits would be a colossal loophole that would swallow the rule because the outcome is one and the same: both kits and standalone frames and receivers can readily be completed, assembled, restored, or otherwise converted to an operational frame or receiver. The text of the Ghost Gun Rule is consistent with other steps ATF has taken to ensure that unfinished frames and receivers are treated as firearms. For example, ATF has rescinded prior determination letters that ruled nearly-complete frames or receivers are not firearms and has required manufacturers to resubmit these parts for review.

Here’s the problem for Blumenthal and his anti-gun buddies; the Justice Department has already argued in at least one court case that the new rule does not cover, nor was it meant to cover, unfinished frames and receivers sold by themselves. A Texas company called Division 80 filed suit to block the rules from going into effect, in essence arguing that the rule was as broad as Blumenthal says it is, and would require the company to cease all operations. Not so, argued the Department of Justice.

“There’s a thriving market of people who want to make their own guns and don’t want to go through licensed dealers,” Liu explained. “Padilla’s entire product line would be wiped out; consumer demand wouldn’t be there.”

“It’s not just about a license,” the attorney added. “It’s about the ability to build a firearm, a right that’s existed since the nation’s founding.”

But Liu’s arguments were undercut by a disclaimer from Justice Department attorney Daniel Riess, after Liu showed Brown a receiver Division 80 sells for an AR-15 style rifle, the most popular firearm in America.

Riess gave the judge a paper with illustrations taken from the ATF’s final rule, outlining what it does and does not consider to be a receiver.

To qualify as a regulated receiver, Riess explained, the part must come with a “jig” or template – typically a piece of plastic that snaps into place to guide the purchaser on where and how deep to drill holes – drill bits and instructions, making the receiver “readily convertible” within minutes to a fully functional firearm.

Division 80’s attorney said he that was news to him, and to be honest I was a little surprised to see that was DOJ’s position as well. But he also argued that they “want the rule to be as ambiguous as possible,” and I think that’s a fair point.

I think Blumenthal’s right that the rule doesn’t just define 80% complete frames or receivers sold in a parts kit to be “firearms”. It’s the “readiness” of the frame or receiver itself to be completed that supposedly defines what turns it into a piece of metal to a firearm regulated under federal law, and the ATF could change its guidance on a whim (or as the result of political pressure). But the ATF’s guidance speaks only of “parts kits”, and says nothing at all about selling unfinished frames or receivers by themselves. It’s not a loophole, per se. These companies are doing what the ATF says is allowed by the rule, after all. It’s just that the rule itself is written so vaguely that it probably could be enforced in the way Blumenthal and his Senate cohorts want it to be.

So why isn’t the Biden administration enforcing the rule as broadly as they could? I wish I knew, but there are a few potential reasons, including the DOJ deciding to start with a more narrow interpretation in the hope that would increase the chances of it being upheld in the courts. Or, from a political perspective, however, maybe Biden decided to implement the rule on a narrow basis now and expand its enforcement at some point in the future when he wants to make the gun control lobby happy or show he’s doing “something” on guns.

Whatever the reasoning, it’s a little early for the DOJ and the ATF to do an abrupt about-face now, and my guess is that Blumenthal’s letter will get a polite, vague, and non-committal response from Garland and Dettelbach. Honestly, given how the courts have started to treat bans on unserialized firearms, gun control activists should be more concerned about the rule being rolled back entirely, rather than how the ATF is currently enforcing it.