Jockeying for attention in a packed primary, Democrats running for their party's 2020 nomination have rolled out expansive gun-control proposals. The Washington Free Beacon tallied which candidates support which plans and examined the evidence for and against the measures supported by the most candidates.

Gun control has been a major feature of the 2020 primary discussion. Rep. Eric Swalwell (D., Calif.) ran his failed campaign on his proposal to ban and confiscate certain guns. Other contenders, like Sen. Cory Booker (D., N.J.), released comprehensive proposals months ago. The conversation has only gotten more heated since the mass shootings in El Paso, Tex., and Dayton, Ohio, with major candidates like senators Elizabeth Warren (D., Mass.) and Kamala Harris (D., Calif.) dropping new proposals.

To get a handle on just what Democrats want to do, the Free Beacon identified gun-control proposals from all 24 candidates currently running. (Find a full list here.) We found that some candidates had ideas unique to them, while other proposals, like an "assault weapons" ban, were popular across the board. In total, the Free Beacon identified 18 gun-control policies that commanded support from at least two candidates.

Many Democratic candidates appear to be taking an "everything but the kitchen sink" approach to gun policy. Proposals like the aforementioned "assault weapons" ban, universal background checks, and federal funding of gun violence research are all popular. Less popular, but still commanding attention, are ideas like making gun manufacturers liable for criminal acts committed by third parties, or instituting a national "waiting period" for gun purchases.

The Free Beacon looked at the research surrounding the eight ideas with the most support among Democratic candidates—the "assault weapons" ban, universal background checks, red flag laws, "high-capacity" mag bans, federal funding for gun research, federal firearm licensing, the "Charleston loophole," the "boyfriend loophole," and gun buybacks—to see what researchers have said about the proposals.

"Assault Weapons" Ban

So-called assault weapons have been a frequent target of gun-control activists over the past 25 years. The definition of assault weapon, however, varies across the states which have implemented a ban on them. In states like California, the definition has continually expanded to include more firearms over the past decade.

Generally, the term is used to describe semiautomatic firearms—especially rifles—that are capable of accepting detachable magazines and have some combination of cosmetic features like a telescoping stock, flash suppressor, or pistol grip. They also generally feature bans on specifically named rifles like the AR-15—the most popular rifle in the United States. The National Shooting Sports Foundation, the firearms industry’s trade group, estimates there are more than 16 million AR-15s and similar rifles already legally owned in the United States, and many of the proposed bans supported by the Democratic candidates would reach beyond those firearms.

Every single Democratic candidate currently running in the presidential primary supports some form of an "assault weapons" ban. The argument generally presented is "assault weapons" are too dangerous for Americans to own and banning them would reduce both general gun crime and mass shootings. Statistics from the FBI's Uniform Crime Report, however, show such a ban, which would primarily affect a subset of rifles, has a low ceiling when it comes to its potential effect on murder in the United States. In the latest report, rifles were used in 403 of the 15,129 murders—about 2 percent.

The Rand Corporation, a nonpartisan think tank, conducted a major review of all of the literature on the effects of various gun policies in 2018. They looked at the available studies for 13 state or federal policy proposals and assessed the evidence on how they effected eight outcomes. In its overview of the effects of "assault weapons" bans, Rand found conflicting answers from studies purporting to answer whether "assault weapons" bans have any effect on violent crime.

"We identified two qualifying studies that estimated the effects of assault weapon bans on different violent crime outcomes," the review said. "One found uncertain effects of such bans on total homicide rates (Lott, 2010); the other found a suggestive effect consistent with assault weapon bans decreasing firearm homicides (Gius, 2014). Considering the relative strengths of these studies, available evidence is inconclusive for the effect of assault weapon bans on total homicides and firearm homicides."

Similarly, the review found two conflicting studies on the effects of such bans on mass shootings. "Gius (2015c) found that these bans significantly reduce mass shooting deaths but have uncertain effects on injuries resulting from mass shootings," the review said. "Using a similar data set, Luca, Deepak, and Poliquin (2016) found uncertain effects of state assault weapon bans on the annual incidence of mass shootings. Based on an assessment of these findings and the relative strengths of these studies, we find inconclusive evidence for the effect of assault weapon bans on mass shootings."

The review did find limited support for the idea that an "assault weapons" ban leads "to short-term price increases and had mixed effects on the production of different classes of banned weapons."

A study authorized by the Department of Justice after the federal "assault weapons" ban expired in 2004 found there was a decrease in crimes committed with guns affected by the ban. However, it attributed that decrease to pistols affected by the ban and found "no discernible reduction in the lethality and injuriousness of gun violence." The study further stated if the ban was reinstituted, its "impact on gun violence is likely to be small at best, and perhaps too small for reliable measurement."

Universal Background Checks and the "Gun Show Loophole"

Since 1993, federally licensed firearms dealers (FFLs) have been required to run a criminal background check on a would-be gun purchaser before completing the sale. Checks are processed through NICS, a federal database of individuals ineligible to purchase a gun by dint of criminal offense, and usually returned within minutes. Since its inception in 1998, NICS has been used more than 230 million times and led to some 1.3 million denials—though prosecutions of those who fail background checks are rare.

Under current federal law, those who are "in the business" of selling firearms—like those who operate gun stores or sell guns for a living—must obtain a Federal Firearms License. Those who are licensed must perform background checks on their customers regardless of the location a sale takes place—whether it’s at a gun store, online, or at a gun show. Additionally, only licensed individuals are able to sell new firearms and transfer guns purchased outside of the state they're located in. Sales on the used market between two unlicensed individuals who live in the same state are not regulated under federal law and the seller is therefore not required to obtain a background check on the buyer—though it remains illegal to for them to sell a gun to someone they believe is a prohibited person.

Currently, 14 states extend background check requirements to private sales of firearms as well.

Research indicates that background checks on net have a small but significant effect on gun crime. In its comprehensive review of the literature, the Rand Corporation found small but statistically significant effects on firearm suicide, although some share of the impact may be muted by an increase in other kinds of suicide. Rand also found that dealer background checks likely reduce firearm homicide, but no evidence that private-seller background checks have any effect.

There is similarly little evidence on how background checks affect mass shootings. Anecdotally, some number of mass shooters—like those at Sutherland Springs, Charleston, and Virginia Tech—acquired their guns after a background check, in spite of disqualifying conditions, an indication that the quality of a universal system is only as good as its underlying records.

The small effect size may in part be because most guns are not purchased from private dealers. A Harvard/Northeastern University survey found that 13 percent of gun owners who had purchased a firearm in the past two years had not needed a background check. Gun-crime offenders are especially unlikely to purchase their guns from either an FFL or private seller: Just 18 percent purchased their gun at all, with just 10.5 percent obtaining the gun from a pawn shop, flea market, gun show, or family/friend.

A lack of compliance also plays a role. Private, small sales are less likely to attract attention from regulators, meaning that the laws may not actually be observed. One study found that 25 percent of individuals who purchased firearms in California, a universal background check state, did not actually undergo a background check. Another study found that in the wake of their own universal laws, neither Colorado nor Washington state actually saw an increase in the number of background checks. A previous Free Beacon review of Colorado records found the number of background checks actually decreased—and at a faster rate than the national average—after the state's universal background check bill went into effect.

Red Flag Laws

In the wake of the El Paso and Dayton shootings, most gun-control proposals have remained legislative nonstarters. But one appears to be garnering the approval of not only Democrats, but also conservative commentators, President Donald Trump, and Senate Republicans: "extreme risk protection orders," a.k.a. "red flag" laws. These laws allow family members, household members, or law enforcement officials, to ask a court to suspend an individual's right to own a gun because they have credible evidence that he poses a threat to himself or others.

The argument for red flag laws is simple. Most gun-control measures target gun users even if they are law-abiding; they therefore impinge upon the rights of the majority of blameless gun owners while failing to do much to target the small subset who actually commit crimes. Proponents argue red flag laws take advantage of the fact that many shooters display warning signs before they harm themselves or others while affording some measure of due process before they are deprived of their rights.

Seventeen states have implemented red flag laws, most in the years since the Parkland high school shooting. Because of its recentness, there is not a huge amount of evidence regarding the effectiveness of red flag laws. Research on the laws in Connecticut and Indiana indicate that they likely prevent some suicides in both jurisdictions.

The experience of just two states, however, may not generalize. A research review from the Rockefeller Institute of Government found there were "not enough [red flag] laws and not enough changes over time to generate stable effect estimates." Another review, published by John Lott and Carlisle E. Moody in the Social Science Research Network, found that red flag laws have "no significant effect on murder, suicide, the number of people killed in mass public shootings, robbery, aggravated assault, or burglary."

Additionally, critics of the laws have expressed concerns that the evidentiary standard used for red flag laws may be too low. Initial confiscation requires only "reasonable suspicion." Lott has claimed "when hearings occur weeks or a month later, about a third of these initial orders are overturned, but the actual error rate is undoubtedly much higher. These laws make no provisions to cover legal costs, and many people facing these charges do not retain counsel." In other words, at least some individuals are being wrongfully deprived of their constitutional rights and face a steep path to redress.

"Boyfriend Loophole"

A majority of the candidates also want to extend the definition of domestic violence to capture situations not currently covered under federal law—something they refer to as the "boyfriend loophole."

In 1994 Congress made it illegal for somebody subject to a restraining order by an intimate partner or the child of an intimate partner to possess a gun. In 1996 it made anyone who has been convicted of a "misdemeanor crime of domestic violence" a prohibited person. The prohibition applies to any misdemeanor that "has, as an element, the use or attempted use of physical force, or the threatened use of a deadly weapon, committed by a current or former spouse, parent, or guardian of the victim, by a person with whom the victim shares a child in common, by a person who is cohabiting with or has cohabited with the victim as a spouse, parent, or guardian, or by a person similarly situated to a spouse, parent, or guardian of the victim."

Critics believe that definition should be expanded to include someone who commits an act of violence against an intimate partner they don't live with or have children with.

The Free Beacon was unable to locate any studies that specifically look at how such an expansion of the federal definition of domestic violence would affect crime rates. A Rand review of studies on the effects of domestic-violence-related prohibitions did find evidence those policies reduce murder rates.

"Policies that make it illegal for particular groups of people to purchase or possess guns are one form of a broad class of policy levers that attempt to reduce the incidence of criminal gun violence," the review said. "Recent research evidence suggests that such laws targeting domestic violence offenders may reduce homicide rates."

Federal Funding for Gun Research

Most Democratic candidates say they will lift the Dickey Amendment and provide more federal funding for gun violence research. The amendment, passed in 1996, prevents the Centers for Disease Control from using federal dollars specifically to "advocate or promote gun control." It was paired with a cut to CDC funding that matched the amount spent on gun studies the previous year.

The amendment was passed after some CDC officials had publicly stated their desire to use research in order to stigmatize gun ownership.

"We need to revolutionize the way we look at guns, like what we did with cigarettes," Dr. Mark Rosenberg, then-director of the CDC's National Center for Injury Prevention and Control, told the New York Times. "It used to be that smoking was a glamour symbol, cool, sexy, macho. Now it is dirty, deadly and banned."

A 2017 research letter published in the Journal of the American Medical Association found the CDC's spending on firearm injury research fell dramatically after the ban. However, it also found the number of gun-related articles published in scientific journals peaked in the years after the ban and remained near that level, though the topic has fallen when viewed as a percentage of overall scientific literature.

"High Capacity" Magazine Ban

Most of the candidates who support an "assault weapons" ban also support a ban on so-called high capacity ammunition magazines. However, the handful of states with magazine bans cap the number of rounds in a magazine between 10 and 15 rounds, which affect the majority of semiautomatic handguns and rifles currently available for sale in the United States. The National Shooting Sports Foundation estimates there are more than 130 million detachable magazines in the United States with more than 30 million capable of holding more than 30 rounds of ammunition.

Given the popularity of combining "assault weapons" bans with bans on "high capacity" magazines, Rand combined the two policies in their review. It similarly found evidence for how a ban on the devices would affect mass shootings or violent crime generally was inconclusive, but there was limited evidence to support the idea a ban increases prices for the devices and affects their production.

The DOJ study of the federal magazine ban (implementing a 10-round limit) that existed simultaneously with the federal "assault weapons" ban could not determine if the ban had any effect on crime.

"Guns with [magazines holding more than 10 rounds] are used in up to a quarter of gun crimes, but it is not clear how often the outcomes of gun attacks depend on the ability to fire more than 10 shots (the current limit on magazine capacity) without reloading," the study said.

It also noted there were some studies with limited scopes that suggested a small percentage of shootings studied involved more than 10 rounds fired. But it concluded there was not enough evidence to make significant estimates on what the impact of reauthorizing the federal ban would be.

"The evidence on these matters is too limited (both in volume and quality) to make firm projections of the ban’s impact, should it be reauthorized," the study concluded.

Firearm Licensing

Fifteen states and the District of Columbia implement some kind of license or certification requirement to either purchase or own a firearm. Proponents of a nationwide licensing requirement, like Cory Booker, argue that it is no different from requiring a license to operate a car—an analogy opponents say does not quite hold, because purchasing a car does not require a permit and driving a car is not a constitutionally protected right.

There is at least some state-level evidence that gun licensing works, possibly by reducing the total number of guns actually purchased. Criminologist Gary Kleck, generally a skeptic of gun control, found that licensing was one of "a few noteworthy exceptions." One widely cited study found that Connecticut's permitting regime reduced gun homicide by 40 percent; another found that when Missouri repealed its own regime, firearm homicide rose by 23 percent. The Missouri effect, comparing gun to non-gun homicides, seems large. The Connecticut study, for its part, is stymied by a suspect methodology.

Still, research on the effect of licensing is far from conclusive. Rand concluded that licenses have an "uncertain" effect on mass shootings, homicide, and suicide. Its review notes that both the Connecticut and Missouri studies "examined only a single state's experience with either adoption or repeal of the law" and so offer "limited evidence that noted differences are due to the change in the law rather than to other contemporaneous influences over each state's suicide rate around the time the law was changed."

Licensing schemes also raise civil liberty and corruption concerns. Massachusetts's gun-permitting regime, one of the most aggressive in the nation, grants police officers discretion to deny a permit—and therefore exercise of a constitutional right—on the basis of ill-specified "credible evidence" that an individual might pose a threat to public safety. New York City has a similarly strict licensing system for handguns that gives broad discretion to police on who is able to obtain one.

"They might as well have a had a hotline: 1-800-GIFTS4GUNS," the New York Post reported last year. "A former city cop spilled his guts Tuesday, telling Manhattan jurors about years worth of bribes he and his fellow officers received for doling out gun permits—everything from cash, prostitutes and expensive watches to baseball memorabilia and exotic vacations."

A federal system would grant similar unilateral discretion to federal law enforcement.

"Charleston Loophole"

Julian Castro, Pete Buttigieg, Amy Klobuchar, Beto O'Rourke, and Jay Inslee voiced support for changing default proceeds, which they've labeled the "Charleston loophole," in campaign statements reviewed by the Free Beacon. While the vast majority of federal background checks take a few minutes to return either a proceed or deny determination, a default proceed occurs when the FBI finds an indication the buyer could be a prohibited person but does not immediately find disqualifying records and asks to delay a gun purchase to further investigate. After three days, if no prohibitive records are found, the sale is allowed to proceed by law.

The man who attacked a church in Charleston, South Carolina, murdering nine people in 2015, obtained his firearm through a default proceed. Democrats and gun-control advocates want to extend the determination period from 3 days to 10 days.

The Free Beacon was unable to locate any research on the potential effects of this specific proposal.

However, an extension of the determination period for default proceeds would not have prevented the Charleston shooter from obtaining his gun: The FBI's failure to locate his disqualifying court record was due to a mistake on the examiner's part, not lack of time to examine his record. Former FBI director James Comey announced in the aftermath of the shooting that the FBI examiner had mistakenly requested records from the wrong jurisdiction.

Additionally, the FBI does not end its background check if it hasn't reached a determination after three days. Instead, it continues until it is able to make a determination on whether the purchaser was prohibited from owning guns. If it finds they were and the transaction went through, the FBI will refer the case to the Bureau of Alcohol, Tobacco, Firearms, and Explosives, who will then retrieve the firearm from the prohibited person—there were 3,960 such retrievals in 2018, according to an FBI report.

The Charleston shooter purchased his firearm two months before his attack. Had the FBI realized its mistake in that time period, it would have sent the ATF to retrieve his firearm.

Gun Buybacks

Gun buybacks—compensating gun owners for turning their firearms over to the government—have garnered notable support among Democrats looking to show that they are tough on guns. These buybacks can either be mandatory, with owners at least partially compensated for their confiscated firearms, or voluntary, with owners giving up their guns for a cash payment. Which form candidates support varies: O'Rourke and Harris want a mandatory program, Andrew Yang and Joe Biden want a voluntary one, and Castro has not said which he backs.

In theory, reducing the stock of guns should make it harder for individuals to obtain them, thus reducing gun crime. The problem is, the overwhelming evidence indicates that gun buybacks do not work.

A 2008 review found that "no empirical research to date has shown significant changes in gun-related crimes due to these programs." Research on buybacks in Milwaukee, Seattle, Sacramento, Buffalo, and other cities find that the programs had little or no effect on gun offenses. In fact, one 2001 analysis argued that gun buybacks might actually increase the number of guns in circulation.

Proponents often point to mandatory gun buyback programs implemented in other countries, like Australia and New Zealand, but these are not instructive experiences. The number of mass shootings in Australia was already very low before the nation implemented a mandatory buyback in the late '90s. Reported effects on homicide and suicide were likely due to a more general violence decline—with the United States also experiencing a similar decline over the same period. New Zealand's program, implemented earlier this year following the Christchurch shooting, has collected about 10,000 of the country's estimated 1.5 million firearms.

There are a huge number of guns in America—the Small Arms Survey estimates nearly 400 million firearms in civilian hands—and buying them back is likely prohibitively expensive. Giving owners just $50 per gun, for example, would cost $200 million to reduce the number of guns in circulation by just 1 percent.

What is more, studies repeatedly indicate that the types of guns buybacks collect, and the owners they collect from, are a totally different population from the guns and owners regularly involved in crimes. In other words, buybacks likely do not target the people most likely to misuse their firearms. This problem persists even with mandatory buybacks, as people who already own a gun for illegal purposes are unlikely to voluntarily hand it over.