When it comes to law enforcement, the U.S. attorney general is the nation’s top dog.

As head of the U.S. Justice Department, the attorney general is in charge of making sure the nation’s laws are followed and enforced. The attorney general also is in charge of making sure the nation’s laws are enforced fairly.

In one of his first acts as president-elect, Barack Obama made history with his choice for attorney general.

Eric Holder is the first African American ever to hold the job.

Holder has made history before. In 1993 he was the first African American to be named U.S. attorney to prosecute crimes in Washington, D.C., and in 1997 he became the first African American to be deputy U.S. attorney general — the Number 2 job in the Justice Department.

In his 33-year law career, the 58-year-old Holder has seen the U.S. justice system from both sides of the courtroom, as a judge and as a prosecutor.

The experience has made him especially alert to the need for laws to be enforced fairly, without regard to race, religion or ethnic background.

He first saw the importance of that when he was still a student in college. Holder was riding in New Jersey in a car with other African American friends when police pulled them over to search for weapons.

There were no weapons, but the stop made an impression on Holder as an example of the law being used wrongly as “a blunt instrument,” as Time magazine later put it.

In the last 50 years, the nation’s attorney general has been at the center of civil rights struggles again and again.

In 1957 President Dwight Eisenhower’s attorney general, Herbert Brownell, wrote the first Civil Rights Act in 80 years, established the Civil Rights Division in the Justice Department and urged the president to send U.S. troops to Arkansas to support black students trying to enter an all-white high school.

When John F. Kennedy was president from 1961 to 1963, his attorney general Robert Kennedy aggressively enforced civil rights laws and sent U.S. marshals to Mississippi to back a court order admitting civil rights pioneer James Meredith to the University of Mississippi.

In 1965, Attorney General Nicholas Katzenbach drafted the Voting Rights Bill pushed through by President Lyndon Johnson, and acquired a court order prohibiting state officials in the South from interfering with civil rights marches.

Civil rights issues are just some of the challenges Holder faces as attorney general.

At the top of his “to do” list will be what to do with the more than 240 prisoners being held at the anti-terrorism prison the U.S. runs at Guantanamo Bay, Cuba — a prison President Obama has vowed to close within a year.

Holder also must decide whether to reverse the Bush administration’s use of “state secrets” arguments to block legal challenges to national security programs and whether to continue an anti-terrorism policy that allowed wiretapping of U.S. citizens.