Jeff Sessions has been sworn in as US President Donald Trump's attorney general.
In a speech at the White House, Trump described Sessions as a man of "integrity and principal" and someone who has devoted his life to the cause of justice.
The Alabama lawmaker was sworn in the morning after the Senate confirmed his nomination.
Sessions resigned his Senate seat shortly after his colleagues approved him on a 52-47 vote.
He faced opposition from Democrats over his record on civil rights and immigration, while Republicans praised his four decades of public service and his commitment to fairness and the rule of law.
In his short speech Sessions vowed to end "lawlessness" adding that the US "have a crime problem" that is a "dangerous, permanent, trend that places the health and safety of the American people at risk".
Jeff Sessions is regarded as one of the most right-wingpoliticians on Capitol Hill and was one of the first elected Republicans to endorse Trump, believing the businessman was the candidate to tackle an issue closest to his heart - immigration.
His career has been dogged by racism allegations.
In 1986, he was blocked from becoming a federal judge after former colleagues testified that he had used the N-word and joked that he thought KKK was "OK until I found out they smoked pot".
Sessions told CNN in 2009 that he had been devastated by the claims, branding them "false" and "distorted".
Donald Trump also announced three executive orders during the swearing-in ceremony, each related to criminal justice.
They included an order to have the Justice Department and the Department of Homeland Security to tackle "criminal cartels" that have spread across the nation.
Trump says the plan will attempt to break the backs of criminal cartels.
He is also asking for a task force to reduce violent crime in America and a plan to stop violent crimes against law enforcement officers.
He calls it a "shame" what has happened to "truly great" law enforcement officers.