The specific duties of a constable can vary widely from one country to the next and even from one locality to the next, although generally constables are considered to hold some law enforcement powers similar to those of police officers and sheriffs. In England, the lowest police rank is a police constable. In the US, the term is usually used to describe and elected peace officer.
The title of constable originated in the Eastern Roman Empire. These constables were responsible for keeping the horses of their masters or superiors. In medieval times, many European countries adopted the term in reference to high-ranking military officers charged with defending a castle.
Today, constables are common in England and other European countries, where they are considered the lowest ranking police officer, or the equivalent of a patrol officer in the United States. In parts of Europe, the title of senior constable can sometimes refer to a police chief. In England and other countries with a British colonial history, every sworn officer may be considered a constable.
A special constable is a volunteer police officer, with the same powers as a regular officer. These individuals serve an auxiliary function and are called upon when a heightened police presence is required. The chief constable is the head of all British police forces.
While police officers tend to have arrest powers simply as a result of their employ as officers, British constables have legal powers of arrest awarded to them by taking an oath. This is a technicality that makes constables in the UK independent legal officials, rather than just employees of a law enforcement agency.
The situation is quite different in the US, where a constable is generally an elected peace officer with less jurisdiction than a police officer or a sheriff. The duties of a constable can vary by locality, although constables in the US are often charged with carrying out the processes of justice. This can include serving subpoenas and summonses for criminal and civil cases and posting eviction and seizure notices.
These services are often performed by private companies, although states such as Texas, Tennessee, Arizona, and Alabama find it more effective that they be carried out by elected constables. These constables may be assisted by deputy constables and constable's officers in carrying out the processes of the courts. There are, however, some exceptions. A few cities have high constables, who serve as the primary police officers of those areas. Additionally, a constable may also be referred to as a marshal in some states, including Texas and Arizona.