The man behind the 1981 presidential assassination attempt that wounded then-president Ronald Reagan and left White House Press Secretary James Brady paralyzed is set to be released from a Washington, D.C., mental hospital on Saturday.

The would-be assassin, John Hinckley Jr., was found not guilty of his crimes by reason of insanity. The attacks, which left four wounded in total, inspired the 1993 Brady Law and had a lasting impact on gun control legislation.

"Clearly, (the Brady law) has been the most important factor in keeping guns away from the people who shouldn't have them,'' former Bureau of Alcohol Tobacco Firearms and Explosives director John Magaw said, according to USA Today. "It was a historic and strong piece of legislation.''

The Brady Handgun Violence and Prevention Act instituted background checks and waiting periods for gun buyers, measures that gun control advocates today say should be strengthened and expanded.

Although Mr. Brady passed away in 2014 due to complications from the assassination, his friends and colleagues credit the law he supported with saving “tens of thousands” of lives.

"There are few Americans in history who are as directly responsible for saving as many lives as Jim,'' said the president of the Brady campaign, Dan Gross, after Brady passed on.

Critics of the legislation say, however, that although the Brady Act introduced landmark violence prevention measures, it had little to no effect on violent crime rates.

Eighteen states already had gun control measures in place when the Brady Act was passed. Researchers at Georgetown University and Duke University compared homicide and suicide rates from 1985-1997 in those states to the 32 states that gained stricter gun control laws when the legislation was passed.

“Our analyses provide no evidence that implementation of the Brady Act was associated with a reduction in homicide rates,” according to the study, which was published in 2000 in the Journal of the American Medical Association. “In particular, we find no differences in homicide or firearm homicide rates to adult victims in the 32 treatment states directly subject to the Brady Act provisions compared with the remaining control states.”

The one exception to the researchers’ overall conclusion, they said, was the suicide rate among older adults, in states where the Brady law instituted more rigorous gun control laws. A recent shift away from waiting periods in many states could negate that progress.

After a number of horrific mass shootings in recent years, including the Sandy Hook massacre of elementary school aged children and the Virginia Tech shooting, gun control advocates say that the Brady Act’s provisions must be even stricter.

Had the Brady law been in place in 1981 when Mr. Hinckley decided to carry out an assassination plot against Mr. Reagan in order to impress actress Jodie Foster, it may not have stopped him from purchasing a firearm, depending on his state’s rules for reporting mental illness.

In 2007, Virginia Tech shooter Cho Seung-hui should have been barred from purchasing a weapon because a judge had ruled him mentally ill in 2005. But due to a Virginia law that states that a person must be committed to a mental institution before they can be prevented from purchasing a weapon, state officials never reported the judge’s ruling to the National Instant Criminal Background Check System (NICS).

A background check would have failed to register Mr. Seung-hui’s insuitability as a gun owner. Thirty-three people died in the Virginia Tech shooting.

Another Brady law loophole is that it only applies to federally licensed gun dealers. Private gun sellers are not obligated to run background checks on their customers. And even if individuals have a record with their state, sometimes those records aren’t included in the NICS database.

“There are significant problems with it [instant background checks], and not only in Virginia," said former National Rifle Association board member, Rep. John Dingell (D) of Michigan. "We're not putting the money into it, the states aren't putting the effort into it, and there is neither the carrot nor the stick to the degree that there should be to require that the records be properly kept."

Meanwhile, a federal judge ruled in July that Hinckley is not a danger to himself or the public and can live full-time at his mother's home in Williamsburg, Va. Hinckley has already been staying at her home for weeks at a time and preparing for the full-time transition.