There are two things we can learn from The New York Times's lead story today on a 2005 law shielding gun manufacturers from lawsuits. The first is that the companies' self-defensiveness is reflexive. The second is that the NRA's biggest ally on Capitol Hill is probably the filibuster.

The passage of the Protection of Lawful Commerce in Arms Act, signed into law by President Bush, effectively drew a heavy curtain on manufacturers. On a number of occasions prior to its passage, company executives were made to offer testimony under oath about how reports criminal behavior and firearms trafficking were handled. Their answers were revelatory — which is probably one reason why NRA CEO Wayne LaPierre called it "an historic victory for the NRA."

Since Senate Bill 397 was introduced into the 109th Congress, the Senate itself has changed substantially. Only 44 of the 100 members that voted on it are still in the chamber. (It was introduced by Idaho's now-infamous Larry Craig.) In April, those 44 were asked to vote on another critical piece of legislation: whether or not to end a filibuster on a compromise background check proposal. It was one of the most substantial gun-related votes in the Senate since the one in 2005 — and it reveals how, under the "traditional 60-vote threshold" of the new Senate, the NRA needs far less support than it once did.

The NRA won that vote despite two key changes. Both the senators who voted in 2005 and those who are new to the body are more likely to back control reforms.

Sitting senators have moved toward gun control measures. Of the 44 senators who voted on both the Manchin-Toomey compromise in April and the 2005 bill, the vast majority maintained the same position on guns. Those who opposed immunity for gun manufacturers all supported increased background checks. Nearly all of those who granted immunity to manufacturers opposed the compromise.

But that distinction is interesting. Seven senators didn't vote in April the way the 2005 vote might have suggested — and they all moved toward a position supporting gun control. They were Sens. Collins, Johnson, Landrieu, McCain, Nelson, Rockefeller, and Warner; five Democrats, two Republicans. Two senators didn't vote in 2005. One, Feinstein of California, supported the compromise. The other, Roberts of Kansas, opposed it.

The new senators are more likely to back gun control as well. That 2005 bill passed on a 65 to 31 vote. Of the 56 senators that are no longer with the body, 36 supported immunity. Eighteen opposed it — meaning they wanted to continue to allow lawsuits against manufacturers. (One abstained.) The senators that replaced those 56 voted to end the filibuster on the compromise bill 33 to 23 — meaning that gun control supporters gained 15 new votes (from 18 to 33) while gun advocates lost 13 (from 36 to 23).

But the standard that the Senate needed to hit was 60 votes, as it so often is. Even a swing of 23 votes — the eight who switched and the gain of 15 new voters — wasn't enough to hit the 60-vote mark.

The two pieces of legislation are not entirely commensurate, of course, with different arguments being made and different political pressures. But each offered a high profile opportunity for senators to demonstrate their loyalty or opposition to the gun industry. And in each case, the gun industry won.

In 2005, the industry mostly won secrecy. According to The Times review of filings from before the bill, executives from gun companies — Browning, Sturm, Ruger, Glock, MKS Supply — almost uniformly denied any complicity in deaths caused by their product. Executives suggested that they had little role in helping law enforcement efforts to stem firearms trafficking ("I don’t even know what a gun trafficker is," an executive from Taurus International is quoted as saying) or cracking down on retailers found to be violating the law. Those companies that did indicate fault backtracked. A Beretta executive's statement that he didn't understand the looseness of American gun laws was blamed on a language barrier. Smith & Wesson's push for increased safety measures following the settlement of a civil suit. The company faced massive backlash and eventually allowed its planned reforms to evaporate.

The biggest winner in April wasn't the companies, of course, it was the National Rifle Association. In its new cover story, "This Is How the NRA Ends," The New Republic claims that the victory may have been an aberration fostered by a lack of willingness to confront the NRA. "The political class often lets old assumptions blind it to shifting realities," Alec MacGillis argues. "And the absolute power of the NRA is one of the oldest and least-tested assumptions in Washington." MacGillis walks through the reasons that power has and will be tested: shifts in support for background checks, the shift in polling after the April vote, a new willingness to speak out in favor of gun control measures.

What MacGillis doesn't mention is that the April compromise on background checks wouldn't have failed had it been up to the majority of the Senate. A "bigger, richer, meaner gun-control movement" has indeed arrived. But one of the best-tested assumptions in Washington these days is that the Senate won't do anything without a 60-vote margin. And in the case of the Manchin-Toomey compromise, that filibuster was the only counter the NRA needed.

Photo: A display of handguns at a news conference held by counties suing gun manufacturers, 1999. (AP)