The law enforcements that I chose are the sheriff's and county law enforcement, federal law enforcement agencies, and the state police department. Every law enforcement agency is unique and has special objectives but they all utilized to enforce laws, provide services, prevent crimes, and to preserve the peace.
Sheriff's and County Law Enforcement primary responsibility is for investigating violent crimes in their jurisdiction routine patrol. The sheriff has many duties to perform in its county. They has power to make arrest within their county, work to prevent crimes, maintain safety of the court, maintain and operate county jails, work to prevent crime, provide assistance to those affected by crime. They are also responsible for supervising inmates and protecting them.
The Federal Law Enforcement Agency is authorized by Congress, to enforce specific laws or attend to specific situations. The Department of Homeland Security and The Department of Justice are agencies that work within the federal agency; both of these branches has numerous federal law enforcement's that reports to them. The general government is prohibited from exercising general police powers due to restrictions in the constitution, due to the fact that the United States is organized as a union of sovereign states, which each retain their police, military and domestic law-making powers.
The state police and highway patrols assist local police agencies, investigate criminal activities that crossed jurisdictional boundaries, provide law enforcement in rural and other areas that don't have local police agencies, and to break strikes and control labor movements.
I feel that all of these agencies are effective because they all serve in maintaining order, responsible of deterring some type of criminal activity and preventing the successful commission of crimes in progress, providing first response to emergencies and other threats to public safety.