Handcuffs

Handcuffs are specialized restraint devices designed to secure a person's wrists in close proximity to one another.

Their primary purpose is to prevent suspected criminals from escaping while in the custody of law enforcement agencies. These devices function through a mechanical locking system involving two cuffs. Each cuff contains a rotating arm that engages with a ratchet mechanism. Once the cuff is closed around a wrist, the ratchet prevents it from being reopened without a specific key. This mechanical design restricts wrist movement to only a few centimeters or inches, making many physical tasks difficult or impossible for the restrained individual.

Contemporary metal handcuffs generally fall into three distinct structural categories. The first type is the chain cuff, where the two metal rings are linked by a short length of chain. The second type is the hinged cuff, which uses a hinge to connect the two parts. Because hinged cuffs allow much less movement than chain cuffs, they are considered more secure by many officers.

The third type consists of rigid solid bar handcuffs. While these are bulkier to carry, they permit several different variations of cuffing. For example, Hiatt Speedcuffs are a type of rigid handcuff used by most police forces in the United Kingdom. Some agencies even add accessories, such as boxes that fit over the chain or hinge, which can be locked with a padlock for extra security.

Materials used in manufacturing vary depending on the required strength and cost. Metal handcuffs are often manufactured from carbon steel, stainless steel, or aluminium. Some modern versions are made from synthetic polymers. In cases where a person has an exceptionally large waistline, standard handcuffs might not reach around both wrists. In these instances, officers may use two separate pairs of handcuffs. They connect one cuff from the first pair to one cuff from the second pair, then apply the remaining open cuffs to the wrists. Manufacturers also produce oversized handcuffs to address this specific need.

Plastic restraints offer a different approach to security and are often called wrist ties, flexicuffs, or zipcuffs. These are lightweight, disposable strips that resemble electrical cable ties. Because they are easy to carry in large quantities, they are well-suited for large-scale protests, riots, or military use.

Airlines have also begun using these plastic restraints to manage disruptive passengers. However, disposable restraints have drawbacks. They must be cut off to allow a person to be fingerprinted or to attend to bodily functions. Some newer plastic models can be opened with a key, but they are generally less strong than traditional metal handcuffs and may be more likely to cause nerve or soft-tissue damage.

Beyond the wrists, law enforcement may use legcuffs to secure a person's ankles.

Legcuffs have a larger inner perimeter than handcuffs to accommodate the anatomy of the ankle. Some models use an elliptical shape to minimize pressure on the Achilles' tendon. Standard leg irons typically feature a longer connecting chain than wrist handcuffs. These are used to prevent running during transport or to manage extremely aggressive behavior. In some extreme cases, officers may use a technique called "hog-tying," where the handcuffs and leg irons are connected. This practice is highly controversial because it has led to deaths from positional asphyxia, resulting in many locations banning or strictly restricting the maneuver.

For higher levels of security during transport, officers often use combinations of different restraints. A prisoner might wear handcuffs augmented by a belly chain, which is a metal, leather, or canvas belt attached to the waist.

The handcuffs are secured to this chain to keep the hands at waist level. This can provide a degree of comfort during long periods of internment while still restricting movement. If a handcuff cover is used to hide the keyholes, the restraint becomes even more severe. For maximum security, a "full harness" may be used, connecting the handcuffs, the belly chain, and the leg irons all together.

Safety and medical considerations are vital when applying these devices. Many modern handcuffs include a "double lock" feature. This uses a detent to stop the cuff from ratcheting tighter, which prevents nerve damage or loss of circulation if a person struggles. There are different types of double locks, including lever locks, push pin locks, and slot locks.

Additionally, the way hands are positioned matters for health. Since the mid-1960s, many agencies have moved toward handcuffing hands behind the back. However, specific departments favor placing palms together to help prevent a condition known as radial neuropathy. Because a restrained person cannot use their hands to break a fall, officers must be prepared to catch them to prevent injury.