Under certain circumstances, officers in many large American police forces are allowed to restrain subjects by their necks. But a small difference in technique can mean life or death for a subject, and can turn an approved hold into a banned restraint.

The most commonly allowed neck restraint is the stranglehold, which is also known as a sleeper hold or a blood choke. The stranglehold is designed to temporarily cut off blood flow to the brain, causing a subject to go unconscious for a short period. It is not meant to impede a subject's breathing.

It's likely that New York Police Officer Daniel Pantaleo was attempting to perform a stranglehold on Eric Garner after officers confronted Garner about selling cigarettes illegally. A video of Garner's struggle with NYPD officers shows Pantaleo bending his left arm around Garner's neck and using his right arm to tighten his grip. But something went wrong. Pantaleo's hold began to choke Garner, who repeatedly told officers he couldn't breathe. He eventually died, partly because of the hold.

In many of the largest American police departments, policies regarding the use of neck restraints are imprecise, resulting in a lack of accountability for officers who use them.

Police departments generally divide neck restraints into two categories. The first is the stranglehold, described above. The second is the chokehold, in which an officer restricts a subject's ability to breathe by applying pressure to the subject's windpipe. Most large police departments don't allow officers to use chokeholds.

A 2007 Justice Department survey found that 46 percent of police departments who serve more than 1 million people allow some sort of hold or neck restraint. A closer look at the use-of-force policies of the nation's six largest police departments reveals variations in how they treat neck restraints.

  • The Los Angeles Police Department forbids chokeholds, but allows its officers to use a stranglehold in circumstances that call for deadly force.
  • The Metropolitan Police Department of Washington, D.C., also bans chokeholds, and allows an officer to use a stranglehold only in extreme circumstances.
  • The New York Police Department bans any chokehold that affects the throat, trachea, or windpipe, or that "may prevent or hinder breathing." It does not specifically ban strangleholds.
  • The Chicago Police Department requires its officers to avoid holds that impede subjects' breathing, and a spokesperson said that neck restraints are not "approved of or taught" by the department. However, no directive expressly forbids all neck holds.
  • The Philadelphia Police department does not allow any neck holds or restraints.
  • The Houston Police Department does not make its policy available to the public.

No robust or complete inquiry into the health concerns surrounding neck restraints exists, according to a 2006 review by the Calgary Police Service of medical, legal, and police literature about strangleholds.

The carotid control hold is the most widely used type of stranglehold. To perform this hold, an officer bends his or her arm around a subject's neck, applying pressure on either side of the windpipe—but not on the windpipe itself—to slow or stop the flow of blood to the brain via the carotid arteries.

Citing medical studies, the Calgary Police report found that the technique can go wrong in two main ways: either when improperly applied, or when a subjects' physical disposition—if he or she suffers from coronary artery disease, for example—makes the hold dangerous. The report also cites a number of studies and police documents that indicate that a properly applied carotid hold is a safe alternative to impact weapons or deadly force.

Here's a deeper look into each department's policy.

Los Angeles. The LAPD officially allows police strangleholds, although it classifies the tactic as a method of last resort. "We don't choke anyone, but we do use a carotid restraint control hold," an LAPD tactics supervisor told the New York Daily News in July. "We cannot use it unless it's a lethal force or deadly force situation."

According to LAPD reports, the hold was used once by its officers in 2010, twice in 2009, and an average of three times a year between 2005 and 2008. The police department did not respond to multiple requests for comment on its policy.

Washington, D.C. As in Los Angeles, Washington's Metropolitan Police officers are not allowed to use neck restraints that hinder breathing, according to D.C. Code. Carotid holds are permitted, but only "when an imminent threat of death or serious physical injury exists, and no other option is available," per the MPD's use-of-force policy.

The MPD does not keep records of neck-restraint complaints against officers, a spokesperson said. But the 2013 MPD Annual Report of the Office of Police Complaints shows that 39 complaints of police chokeholds were brought against the department between 2009 and 2013. Of the 64 complaints that went through the official examination process between 2009 and 2013, none had to do with neck restraints.

New York. The NYPD's use-of-force policy is less precise than the MPD's or the LAPD's. While the NYPD does not allow its officers to use any sort of hold that applies "any pressure to the throat or windpipe, which may prevent or hinder breathing or reduce intake of air," there is no rule that directly addresses restraints such as the carotid hold, which are not meant to impede a subject's breathing.

In New York, confusion over the exact definition of a chokehold and infrequent enforcement of the chokehold ban have resulted in continued use of the tactic—despite a two-decade-old ban—according to an October report from the New York City Civilian Complaint Review Board. Rather than upholding what the CCRB calls an "unequivocal prohibition of any pressure to the neck which 'may' inhibit breathing," the NYPD's lax enforcement policies have allowed the directive to devolve into a much less stringent ban that covers only "actual and sustained interference with breathing."

Between July 2013 and June 2014, the CCRB received 219 chokehold complaints, according to the report.

Chicago. In Chicago, policy is also vague. Police officers are not trained in any neck restraints, said a spokesperson for the Chicago Police Department. Department use-of-force directives state that officers must "position the subject in a manner to allow free breathing," and neck restraints are not mentioned in the list of authorized force options. Such restraints are not, however, specifically prohibited.

This week, members of the Chicago City Council proposed an ordinance that would ban neck restraints more explicitly. The ordinance, seemingly modeled on the NYPD's policy, reads in part: "A chokehold shall include, but is not limited to, any pressure to the throat or windpipe, which may prevent or hinder breathing or reduce intake of air." It still allows for use of the tactic when an officer is "faced with a situation in which the use of deadly force is justified under applicable law." This wording could lend itself to the same lax enforcement that has made a neck-restraint ban ineffective in New York and set up the confrontation that led to Eric Garner's death.

The Chicago Police Department does not make data about neck-restraint complaints available to the public. The most recent public complaint was a 2000 incident that was brought to court in a 2006 case. In the incident, a man died after he was arrested following a high-speed car chase. A medical examiner later said the man "died as a result of asphyxia due to a choke hold." The subject's family filed suit against the police department, but did not win the case.

Philadelphia. The only police department in the group to make public a specific ban on all forms of neck restraints is the Philadelphia Police Department. According to a spokesperson for the department, "the intentional use of neck restraints (choke holds, 'sleeper holds' or other holds to render a subject unconscious) are prohibited." The spokesperson also said that "the police academy tells the recruits NOT to use the neck restraints." The Philadelphia Police Department does not make complaints about police using neck holds available publicly.

Houston. The Houston Police Department would not comment on its use-of-force policy, which is not publicly available. National Journal's open-records request for the policy is pending.

In the wake of the Eric Garner case, where an officer's neck restraint led to the death of a subject, use-of-force policies have come under increased scrutiny, leading to actions like the Chicago City Council's move to tighten up rules for police. But unless such changes come with precise wording and officers are held accountable for violations, the use of neck restraints could continue relatively unchecked.

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