Brazil judge Joaquim Barbosa took the oath of office as Brazil's first ever black head of the Supreme Court on Thursday, in a historic ceremony attended by President Dilma Rousseff and other top leaders.

The son of a bricklayer and a cleaner, Barbosa, 58, pledged in his swearing in "to fulfill the duties of the office of the President of the Federal Supreme Court and the National Council of Justice under the law."

Barbosa's elevation to the top judicial post in Brazil, the last country in the Americas to abolish slavery, in 1888, has been heralded as a breakthrough.

Despite constituting a majority of the population, Afro-Brazilians languish at the bottom of the socio-economic ladder.

Barbosa shot to fame as the court's most vocal critic of a congressional vote-buying scheme laid bare in an ongoing trial -- dubbed "Mensalao" or "big monthly payments" -- of former president Luiz Inacio Lula da Silva's top aides.

The scandal nearly cost Lula re-election in 2006, but the 66-year-old founder and leader of the leftist Workers' Party was cleared.

The former president also originally nominated Barbosa to join the top court, nine years ago, after his performance in a so-called "trial of the century" secured his reputation as an implacable fighter against corruption.

Barbosa, who earned a PhD in public law at the French Sorbonne university, replaced Carlos Ayres Britto, who retired at age 70.