Senator Bernie Sanders agreed Thursday to cosponsor a bill repealing a 2005 law that shields gun businesses from civil liability, but the presidential candidate continues to offer dubious explanations for his past support for the measure.

Sanders’s about-face on the issue won’t help the bill — which is already sponsored by Connecticut Democratic Senators Chris Murphy and Richard Blumenthal — overcome Republican opposition in this Congress. What it might do, he hopes, is diffuse months of rival Hillary Clinton’s attacks on his gun record. The former Secretary of State has used Sanders’s past support for giving gun businesses immunity to raise doubts about his liberal bona fides among Democratic primary voters who are largely aligned in support of stronger gun laws: A New York Times-CBS poll this month found that 82 percent of Democrats support stronger gun restrictions, up from 70 percent of Democrats who said they backed stricter laws in December 2013.

Dan Gross, president of the Brady Campaign to Prevent Gun Violence, described Sanders’s move as “proof of what can happen when the public holds politicians accountable — which is happening on the gun violence prevention issue like never before.”

Sanders’s efforts to explain his past gun votes has led a candidate running as a bold truth teller into uncharacteristic evasions. He has struggled to articulate why he voted for the Protection of Lawful Commerce in Arms Act (PLCAA), enacted in 2005, which prevents lawsuits against gun manufacturers and sellers for crimes committed with firearms that they sold.

In a Democratic forum on Monday, a week before the Iowa caucuses, Sanders said he had supported PLCAA because, “among other things, it has a section which says we should not be selling ammunition which will pierce policemen’s armor.” He said he also liked a PLCAA provision “which said that we want to have safety locks for children on guns.”

The details formed a new line of argument for Sanders. But it’s one that does not withstand scrutiny.

The Senate added the child safety and armor-piercing bullet provisions to the measure in July 2005 votes. The bill then passed in October 2005. But a 2003 version of the bill did not contain either of those provisions. Sanders, then a member of the House, voted for it anyway.

The provisions he was referring to during the town hall are also laden with caveats. The bill added penalties for possessing armor-piercing bullets only when they are used during a violent or drug-related crime. And the child safety provision has never been enforced.

During Monday’s forum, Sanders also repeated a line he’s said many times on the campaign trail: He voted for PLCAA because it prevents the owner “of a small gun shop in Vermont” from being held liable for a crime committed with a gun that he or she sold. Sanders distinguished the hypothetical small gun shop owner from a large firearm manufacturer that sells “a whole lot of guns into an area, far more guns than that area can consume.” In that case, or if the seller “should know that those guns are going into criminal hands,” the company should be liable, Sanders said at the town hall. He said he backed PLCAA despite the fact that it also exempted large gun makers from liability.

Explaining his decision to support a repeal of the 2005 law, Sanders added, “I am willing now to look at that legislation, maintain what was good in it, get rid of what is bad in it.”

But the distinction between small gun shops and big gun makers ignores an important reality of the gun market, as The Trace has earlier noted: Gun manufacturers distribute their products through local firearms dealers. A study from the Bureau of Alcohol, Tobacco, Firearms, and Explosives found guns from small shops sell roughly 69 percent of guns later resold on the black market.

The PLCAA repeal bill that the Democrats have offered, however, has no exemption for small gun sellers. It simply scraps the entire 2005 law. Since Sanders is backing it anyway, he is reversing his former position, rather than maintaining support for “what was good” in the bill.

Timothy Lytton, a professor of law at Georgia State University who edited “Suing the Gun Industry,” a book about using lawsuits to reduce gun violence, dismissed Sanders’s explanation. The 2005 law, which followed similar laws enacted by states, “granted immunity to firearms manufacturers and retail sellers for lawsuits arising out of criminal misuse of the weapons,” Lytton told The Trace. “That is what the legislation was about. Anyone who says anything else is mischaracterizing it.”

“Bernie Sanders likely voted for it because he had a lot of pressure from gun rights advocates in his state, not because he thought it would make children safer,” Lytton said. “It had nothing to do with making children safer.”

The Sanders and Clinton campaigns declined to comment.

[Photo: CQ Roll Call via AP Images]