Black people are being systematically and intentionally excluded from jury service in parts of Alabama almost 140 years after the practice was outlawed in the US, a lawsuit lodged with the federal courts alleges.

The class action has been launched on behalf of thousands of black people in Alabama who were allegedly prevented from sitting as jurors in serious criminal cases, many of which carried the death penalty, in a blatant move by prosecutors to achieve all-white or largely white juries. The complaint claims that the practice has been going on for decades.

It relates specifically to the actions of one prosecutor, Douglas Valeska, who is district attorney in the Alabama counties of Houston and Henry. The lawsuit alleges that he, together with his unnamed associate prosecutors, effectively relegated black people in their areas to "second class citizenship".

Valeska was not available for comment. He told the local Dothan Eagle newspaper that the lawsuit was a "a filing by ambush. It looks like they're trying to try their case in the media."

Alabama has the highest execution rate per capita in America, and within the state Houston County is the most friendly towards the death penalty. This county alone has sent more prisoners to death row than than the states of Maryland, South Dakota, Montana, Wyoming, New Mexico, and Colorado combined.

The lawsuit has been filed by the Equal Justice Initiative, a non-profit group that provides legal support to prisoners unfairly treated by the system. It says that the alleged discriminatory behaviour in Alabama is replicated widely across the south as a hangover from the days of segregation.

Racial discrimination in jury selection was banned under the 1875 Civil Rights Act, but prosecutors in many southern states continued to achieve all-white juries through the use of pre-emptive ruses that excluded black people through the application of seemingly non-racial criteria.

An investigation by EJI last year found that racial discrimination was still rampant in courtrooms across Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, South Carolina and Tennessee.

The lawsuit alleges that Valeska and his assistant prosecutors were liable for "continuing, systemic violation of state and federal law" involving "racial discrimination and unequal treatment". It says that though 24% of the population in the two Alabama counties was black, only 5% of the jurors sitting on death penalty cases prosecuted by Valeska and his team in those areas was African American.

It further alleges that the prosecutors intentionally struck off 82% of the eligible black jurors in death penalty cases between 2006 and 2010, leading to juries that were all white or had only a single black juror.

The plaintiffs in the new Alabama lawsuit are five black people who fell foul of discriminatory jury selection in the two counties. They include Freddie Russaw, 57, who served 22 years in the US military.

He was called for jury service in 2004 for a case carrying the death penalty. Court documents filed in the lawsuit allege that black jurors were singled out for questioning before the trial started and in the outcome eight black people, Russaw included, were kept off the jury, as well as one Asian American and only one white.

Another plaintiff, Vick Brown, an accountant aged 35, was struck off the jury in 1995 because the defendant wanted to avoid an "all black jury".

"Removing people from a jury on the basis of race is shameful and inexcusable. Many times you cannot do anything about discrimination – especially when it is committed by public officials who know how to disguise and justify their behaviour," she said.

In all five plaintiffs' cases, higher courts in Alabama later censured the removal of the black jurors finding that the move had been improperly motivated by race.

Bryan Stevenson, the EJI lawyer leading the class action on behalf of the plaintiffs, said that discrimination over juries was particularly significant because a disproportionate number of defendants in death penalty cases were themselves black. As for why there should be a preference for white jurors within the judicial system, he said: "There is a fundamental distrust of black jurors among some prosecutors. They want people to sit on the jury who are so trusting of the police that they will not question the charges, and there's a presumption held by some that black people don't fit that definition."