In the wake of the Islamist terror attack that killed 50 people at a gay nightclub in Orlando, Hillary Clinton and congressional Democrats are vigorously pushing legislation to ban American citizens from purchasing guns if the federal government has a reasonable suspicion the gun may be used in a terrorist attack.

Some leading Democrats contend that the legislation would have prevented the Orlando attack, but that claim is highly dubious. As Democratic Florida senator Bill Nelson told reporters on a conference call today, the FBI twice investigated the Orlando killer, Omar Mateen, but closed both investigations because "there was no prosecutable evidence." Mateen was not on a government watch list at the time of the attack.

New York senator Chuck Schumer admitted that "we'll never know" if the bill could have kept a gun out of the killer's hands. "The language says basically ... that if the FBI believes there's a reasonable chance someone is going to use a gun in a terrorist attack, it should be able to block that sale. In other words, even if the criteria for some of the no-fly and watch lists may not be met, these criteria could prevent the sale," Schumer said during Monday's conference call. "Would they have blocked Mateen's gun? I think it's likely they would have. But we'll never know because this law was not on the books."

As THE WEEKLY STANDARD reported back in December, Senate Republicans proposed alternative legislation that required the government to establish "probable cause"—the same standard used to obtain a search warrant—to deny the sale of a gun:

The Democratic proposal relies on a secret list and mere suspicion to strip some Americans of their constitutional rights. It provides no process for Americans wrongly placed on the list to get their names removed. The FBI is already alerted during the criminal background check process anytime someone on the watch list tries to purchase a gun, and it is already illegal for almost all of the people on the list to buy a gun. According to the National Counterterrorism Center, only 25,000 of the 1.1 million people on the watch list are U.S. citizens and legal permanent residents, and the Gun Control Act generally prohibits both illegal aliens and legal aliens who have "been admitted to the United States under a nonimmigrant visa" from buying guns. There have nevertheless been some high profile cases of innocent U.S. citizens—including former senator Ted Kennedy and The Weekly Standard's Stephen F. Hayes—being erroneously placed on the terror watch list. What's been lost in the debate is the fact that Republicans have an alternative to the Democratic proposal. Under Republican legislation sponsored by Senator John Cornyn, the federal government may delay the sale of a firearm to someone on the watch list for up to 72 hours. During that time, if the government can show a judge there's "probable cause"—the same legal standard used to obtain a search warrant—that the individual is plotting terrorism, then the gun sale is denied outright. The measure received 55 votes in the Senate. It secured the backing of staunch conservatives like Ted Cruz, Mike Lee, and Marco Rubio as well as moderate Republicans Susan Collins and Lisa Murkowski and moderate Democrats Joe Manchin and Joe Donnelly. The only Republican to oppose it was Mark Kirk. The Democratic bill sponsored by Senator Diane Feinstein, by contrast, simply allows the federal government to ban anyone on the watch list from buying a gun. The government's decision may be challenged in court by the prospective gun buyer, but the government's decision will be sustained if a "preponderance of evidence" indicates that the attorney general has a "reasonable belief" that the prospective gun buyer may be engaged in terrorism. In other words, the GOP bill puts the burden on the government to get judicial clearance, while the Democratic bill puts the burden on the individual to prove his innocence. The GOP bill requires the government to show "probable cause" to a judge, while the Democratic bill relies on a lower legal standard that a "preponderance of evidence" shows the attorney general has a "reasonable belief" that the prospective gun buyer may be a terrorist.

Schumer claimed the Cornyn bill would allow someone on the watch list to immediately obtain a weapon, but that claim was false: The sale would not go through for 72 hours. Democratic claims that lawyers could delay a hearing beyond 72 hours in order to get around the law proposed by Cornyn were also unfounded. As Ken White, a criminal defense attorney and former federal prosecutor who writes at the libertarian-leaning Popehat.com, said: "I see nothing suggesting that the defense lawyer can demand a continuance or say 'I'm not available that day.' And I imagine if this passed courts would come up with a procedure—probably magistrate judges for the feds, just like for search warrants and complaints."

Harry Reid and Nancy Pelosi have never explained why they decided not to bring the Democratic terror watch list gun ban up for a vote when Democrats controlled overwhelming majorities in the House and Senate from 2009 to 2011.