Law Enforcement refers to ensuring obedience to laws. It is the maintenance of public order by implementing laws, administration of the laws of the land.
In US there are a number law enforcement agencies (LEA) which are chartered and empowered to enforce laws. Each state and county or city has its own LEAs. Examples of law enforcement agencies are Federal Bureau of Investigation(a federal law enforcement agency that is the principal investigative arm of the Department of Justice), Drug Enforcement Administration, Drug Enforcement Agency (DEA) – (federal agency responsible for enforcing laws and regulations governing narcotics and controlled substances whose goal is to immobilize drug trafficking organizations), Federal Judiciary - the judiciary of the United States which is responsible for interpreting and enforcing federal laws, the police department etc.