A trigger lock is a device designed to prevent a firearm

Firearm

A firearm is a weapon that launches one, or many, projectile at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically...

 from being discharged while the device is in place. Generally, two pieces come together from either side behind the trigger and are locked in place, which can be unlocked with a key

Key (lock)

A key is an instrument that is used to operate a lock. A typical key consists of two parts: the blade, which slides into the keyway of the lock and distinguishes between different keys, and the bow, which is left protruding so that torque can be applied by the user. The blade is usually intended to...

 or combination

Combination lock

A combination lock is a type of lock in which a sequence of numbers or symbols is used to open the lock. The sequence may be entered using a single rotating dial which interacts with several discs or cams, by using a set of several rotating discs with inscribed numerals which directly interact with...

. This physically prevents the trigger from being pulled to discharge the weapon. Other types of trigger locks do not go behind the trigger, but encompass the full area behind the trigger guard

Trigger guard

A trigger guard is a loop surrounding the trigger of a firearm and protecting it from accidental discharge.Some assault rifles can have their trigger guard removed or positioned as not to impair firing with gloves for example in Arctic conditions....

 making the trigger inaccessible.

There is controversy surrounding manufacturing standards, usage, and legislation of trigger locks. While supporters of trigger locks argue that they will save children from dying in gun accidents, critics point to demonstrations that some models can be removed by children with very little force and common household tools. Many firearms can go off if the gun is dropped. It is important to make sure to look for firearms that fully disengage the hammer when the safety is put on. A former senior product manager at Master Lock, a trigger lock manufacturer, was quoted as saying “If you put a trigger lock on any loaded gun, you are making the gun more dangerous.” Critics also point out that a trigger lock will increase the time it takes a gun owner to respond to a self-defense emergency. In 2008, the U.S. Supreme Court overturned a Washington, D.C. law

District of Columbia v. Heller

District of Columbia v. Heller, 554 U.S. 570 , was a landmark case in which the Supreme Court of the United States held that the Second Amendment to the United States Constitution protects an individual's right to possess a firearm for traditionally lawful purposes in federal enclaves, such as...

 that required handguns to be locked or otherwise kept inoperative within the home, saying that this "makes it impossible for citizens to use them for the core lawful purpose of self-defense."

Although there are no universal standards for the design or testing of trigger locks, some jurisdictions, such as the state of California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, maintain a list of approved trigger lock devices. In Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, a trigger lock is one of the methods prescribed by law to secure a firearm during transport or storage.

External links

• http://depts.washington.edu/lokitup/locks.html
• http://w3.agsfoundation.com/s_lock1.html