On Orlando and guns, talking (and tweeting) but not much doing

After 15 hours of talking by Connecticut Sen. Christopher S. Murphy and his allies and 140 characters of tweeting by Donald Trump, the idea that Congress could actually act on proposals to ban people on the federal government's terrorist watch list from buying guns gained some traction this week. But if you're hoping that the nation's worst mass shooting would inspire lawmakers to enact legislation that could have actually stopped Omar Mateen from spraying an Orlando nightclub with bullets last weekend, don't hold your breath. History suggests the Senate (not to mention the House) will do a lot more talking and tweeting than doing when it comes to responding to last weekend's shootings.

The Government Accountability Office reported in March that at least 2,477 people on the government's watch list have tried to buy firearms or explosives since 2004, and 2,265 of them succeeded. And it wasn't because of suspected terrorist ties that those 212 were rejected; they failed for reasons that would have disqualified them anyway, like criminal convictions. The FBI is informed when someone on the watch list tries to buy a gun, and since 2005, it (rather than a state agency) has handled the National Instant Criminal Background Check System query for those cases, but nothing in federal law stops those sales, even for those on the more restrictive no-fly list.

The amendments Mr. Murphy was championing might in fact have done some good in this case. Not only would they ban gun sales to those on the terror watch list but they would also expand background checks to private sales. Presently in most states, a terrorist, a felon or anyone else could use what's known as the "gun show loophole" to buy a firearm without being subject to a background check. Meanwhile, by itself, enacting the terror watch list gun sales ban wouldn't have had any effect — Mateen had been on it years before when he had come under scrutiny by the FBI, but he dropped off after authorities found no conclusive evidence linking him to terrorism. That's why the current version, authored by California Sen. Dianne Feinstein and Vermont Sen. Patrick Leahy, extends the prohibition to anyone who has been the subject of a federal terrorism investigation within the last five years.

That would have covered Mateen, but it may also make the measure impossible to pass. Some civil liberties advocates were leery of previous versions of this legislation, fearing a slippery slope to the denial of other rights to people who have not been convicted of a crime. We believe that concern is misplaced, given the precedent of denying gun purchases to those who suffer from mental illness, but adding a five-year retrospective clause to the legislation could rob the measure of crucial Democratic votes, without which it is assuredly doomed.

It's probably doomed anyway. The Senate voted on the previous version of the watch-list legislation in December, after the San Bernardino shootings, and it failed 45-54, with one Republican in favor and one Democrat opposed. Nothing appears substantively to have changed in the voting lines.

Republicans, despite some talk about seeking a compromise, appear unwilling to back anything like a workable solution. We don't know quite what Mr. Trump meant when he wrote, "I will be meeting with the N.R.A., who has endorsed me, about not allowing people on the terrorist watch list, or the no-fly list, to buy guns," but we are pretty sure what he'll discover when he sits down with the group, which shows now signs of abdicating its agenda-setting role for Republicans on Capitol Hill. It has supported an approach currently being pushed by Republican Texas Sen. John Cornyn that would only give the federal government three days to prove that someone on the watch list should be banned from buying a gun — a timetable that would be all but impossible to meet.

Often after mass shootings, the nation is at a loss to pinpoint a policy response that could have prevented that particular case of violence, but not this time. The measures Mr. Murphy fought for — plus a renewal of the federal ban on assault weapons, which appears inexplicably to be off the table altogether — might well have made a difference for the victims in Orlando. All that's lacking is a willingness by Congress is to keep Americans safe.