Police are the enforcers of law in a society. Their job entails investigating crimes and arresting criminals to be brought to trial. The police work with prosecuting attorneys. The job of the police is to investigate and arrest criminals and show the prosecuting attorneys evidence against the criminals, while the prosecuting attorneys job is to prosecute the criminal on behalf of the government and persuade the judge and/or jury to convict the criminal. The police also act as witnesses to crimes and are often called upon to give evidence against a criminal. Police are required in every civilized society, as they are necessary to enforce the Rule of Law. Police are also known as constables, inspectors, sheriffs, and troopers. Each has a specific function as deemed by their respective governing agency. Police have rights that give them the ability to perform their duties. They vary between different countries and states. Usually they have the right to detain people, arrest people, search property, and search houses. When a police officer is in the place he has the right to use his power, he is in his jurisdiction, if he wants to arrest a person outside his jurisdictions, the other jurisdiction's police must do it for him. Police usually have weapons such as guns, batons, and pepper spray. The job of the police is to stop crimes from happening and protect the public from criminals. They also direct traffic and usually assist other emergency services in non-criminal emergencies such as fires also. Police are usually divided into detectives and uniformed officers. Uniformed officers patrol on foot and in marked police cars in order to deter people from committing crime, make the community safer, and direct traffic. Uniformed detectives drive in unmarked cars to investigate crimes undetected.
The history of the police as a job function dates back beyond the Roman and Greek eras. Prior to this, the function of law and order was left to the particular nobles to protect their own lands. During the Roman Empire, law and order was more organized, as the military performed this function. In ancient Rome, the Praetorian Guard acted as the police force.
The first modern police force was founded in Paris, France during the reign of King Louis XIV. He created this body in 1666. Nicholas Gabriel de La Reynie was the first Paris police administrator. In London Patrick In 1797, Patrick Colquhoun was able to persuade the West Indies merchants who operated at the Pool of London on the River Thames to found a police force to prevent theft that was damaging his company and others.  This force was called the Thames River Police and was the first modern police force in Great Britain. It inspired similar police in Dublin, Sydney, and New York City. When London's population exploded during the Industrial Revolution, Sir Robert Peel began organizing changes in law enforcement. Royal Assent to the Metropolitan Police Act was given, and the Metropolitan Police Service was established on September 29, 1829 in London as the first modern and professional police force in the world. In 1836 the British Parliament passed the Dublin Police Act, which created the Dublin Metropolitan Police Department.  The South Australia Police was created in 1838 and headed by Henry Inman.
- Clark, David Encyclopedia of Law and Society: American and Global Perspectives page 1122
- [Dick Paterson, Origins of the Thames Police, Thames Police Museum. Retrieved 4 February 2007.http://www.thamespolicemuseum.org.uk/h_police_1.html]
- The National Archives | NDAD | Metropolitan Police. Ndad.nationalarchives.gov.uk. Retrieved on 2009-05-08.