In many areas, anti gun rights politicians and organizations have mandated waiting periods before a gun can be purchased.  They argue that his will provide time for an angry person to “cool off” so that they don’t go buy a gun and commit a crime, and that this time is needed to run a background check.  These arguments may seem persuasive at first, but are in fact rather weak and poorly reasoned; failing to prevent crime and instead leaving citizens who need a gun for self defense in a vulnerable position:

The flaws in the “cool off” period argument
The first justification given for waiting periods is that they prevent an angry person from immediately buying a gun and killing someone, such as an unfaithful spouse or bad neighbor.  This argument fails upon careful analysis.
1. The reality of the situation is that guns are already widely available, as about 1/2 of households in the USA already have guns.  Also, guns (like illegal drugs) are readily available on the black market. The people who are bent on committing a crime such as murder can use a gun they already own, buy one on the black market, get one from a friend, steal one, or use another equally deadly tool to commit murder.  Indeed it is rare to find murders that were committed by people who just lawfully bought a gun without a chance to “cool off”.
2. The “cool off” period argument also fails to recognize that people commit murder and other crimes with a variety of tools other than guns.  Some killings are committed using bathtubs and water, while others involve gasoline.  Given the fact that most of the “heat of the moment” crimes that waiting periods are supposed to prevent are committed by a person the victim knows, that person is usually able to get close to the victim and surprise them.  With the element of surprise on the side of the attacker, just about any object can be used as a deadly weapon.
3. Another problem with this argument is that it assumes that all gun purchasers are irrational and murderous people who have no control over their emotions.  This approach fails to take personal responsibility into consideration, instead blaming inanimate objects for the crimes of humans.  By that logic, we need waiting periods for cars, nail guns, hammers, gasoline, dogs, blunt objects, and every other object in everyday life that could potentially be used to kill.

The flaws in the “background check” period argument
Another justification given for waiting periods is that time is needed to run background checks, in order to prevent convicted felons and other prohibited people from buying a gun.  This argument also has logical flaws.
1. Background checks can be performed in a matter of seconds using the National Instant Criminal Background Check System (NICS), meaning that there is no need to delay the purchase of a gun by more than just a few seconds.  When I purchased my second shotgun I measured the amount of time it took the gun store employee to complete the background check, and it was under 1 minute.  We live in a computerized world, and delays in looking up information are no longer reasonable nor necessary.
2. Background checks don’t stop criminals from buying guns, because criminals tend to buy their weapons illegally, or to acquire guns in other illegal ways. It is also obvious that illegal gun dealers certainly don’t run background checks, any more than an illegal drug dealer would ask to see a prescription.  Instead, as law abiding citizens are filling out paperwork, submitting to background checks, and and being forced to wait, criminals buy their guns with no delays.

The result: Citizens who need guns for self defense right away are left vulnerable
There are countless cases in which a law abiding citizen suddenly comes to fear for their safety, and would like a gun.  One such example is that of Doris Murray of Georgia, whose former boyfriend was charged with her murder after she is believed to have tried to end their relationship.  Contrast that with Terry Jackson, Rayna Ross, or this woman, who all had abusive ex boyfriends that ignored orders of protection to attack these women in their homes – but these women had just gotten guns, and were able to save their own lives by shooting in self defense.
In other cases, citizens don’t perceive any threat in particular but would like to have a gun for self defense.  Many people make this intelligent decision after an unarmed love one suffers at the hands of criminals.  Such people are also forced to wait, and may become crime victims themselves during that time.
It is also worth noting that the majority people killed by abusive former partners are women, who statistically tend to be less physically strong than their male abusers.  That means that even if waiting periods or other gun control laws were to keep guns out of the hands of violent criminals (which they don’t), these women could still be physically overpowered and stabbed to death by their attackers.  As I’ve said before, gun control is sexist.

An example of pointless waiting periods in action: Illinois
An Illinois citizen who wants a gun will have to wait about a month and possibly longer.  This may be the difference between life and death for those faced with a violent stalker:
First, an Illinois resident who wants to lawfully own a gun needs to apply for a Firearms Owner Identification Card (FOID).  This application requires that the citizen submit a recent picture, along with a whole host of other information.  The Illinois State Police then take about a month to run a background check and mail the citizen their FOID card (this same background check is automatically re run every single day by the Illinois State Police, who will come and seize a citizen’s guns if they commit a crime, are indicated for a felony, are subject to an order of protection, are adjudicated mentally ill, etc.)  With their new FOID card in hand, the citizen can then go to their local gun store, fill out paperwork, pass another background check, then be forced to wait another 24 hours (for rifles/shotguns) or 72 hours (for handguns).  As I experienced, the waiting periods apply for those who own guns already, which cannot be rationally justified at all.
Since the background check was already run by the state police before the FOID card was issued, and since it is re-run every single day, there is no point to the background check and waiting period, other than the anti gun groups’ goal of making gun ownership more difficult for law abiding people.
Criminals in Illinois, such as those who have caused an 18% increase in Chicago’s murder rate in 2008, don’t have to apply for a FOID, pass a background check, or wait up to 3 days to get their guns.  Instead, they just buy an illegal gun from the same criminals who sell drugs or other contraband, making those criminals better funded and more able to commit other crimes.

Conclusion
Waiting periods do not keep guns out of the hands of criminals, or prevent “heat of the moment” killings.  They are not needed to run background checks, as those are now done instantly through the NICS. Instead, they leave law abiding citizens vulnerable to criminals and abusive ex partners, and bear no relationship to background checks or public safety.  Anti gun groups push such waiting periods as just another way whittling down the Second Amendment right to keep and bear arms for self defense.