Three US former drone operators on Thursday joined a lawsuit against US President Barack Obama over the deaths of innocent Yemenis in US drone strikes.

The brief, filed by Brandon Bryant, Lisa Ling and Cian Westmoreland, said the veterans had “witnessed a secret, global system without regard for borders, conducting widespread surveillance with the ability to conduct deadly targeted killing operations.

“From their collective experience working on the drone programme...[they] believe the public has been misinformed about the effectiveness of drone strikes and the way they are conducted.”

The evidence was submitted in support of a lawsuit filed by Faisal bin Ali Jaber, a Yemeni environmental engineer whose brother-in-law and nephew were killed in a drone strike on his village in 2012.

Jaber's brother-in-law, Salem, was a preacher who gave a sermon denouncing al-Qaeda's ideology a few days before the deadly strike on 29 August 2012.

Salem and Jaber's nephew, a 26-year-old police officer with a wife and young child, were killed while meeting a group of men thought to have been al-Qaeda sympathisers.

Jaber says he was later given $100,000 in cash by a Yemeni official, a tactic reportedly used to repay victims of the secretive US drone programme.

Jaber described his relatives as “innocent” collateral damage in the strike, and said that at this point, he is only seeking an official apology, but that has not been forthcoming.

Jaber is jointly represented by the international human rights organisation Reprieve and pro-bono counsel at the law firm Lewis Baach pllc. The three ex-drone operators are represented by attorneys at the Whistleblower & Source Protection Program (WHISPeR).

In a statement released by Reprieve on Thursday, one of Jaber's lawyers, Eric Lewis, said: “President Obama has rightly said that the United States must face up to its mistakes in the drone killing programme: here is an opportunity. The drone strike that killed Faisal's family was taken in violation of both US and international law.

"There was no 'imminent threat' to the US, and there was a clear probability of needless civilian deaths. It is time for innocent drone victims to be treated with dignity by our government. This includes telling bereaved families the truth about how and why their loved ones died.”

In June, the US president said that drone and other air strikes have killed between 64 and 116 civilians during his administration, but at the same time he acknowledged that the government itself does not always know how many civilians it kills and that it may revise its death tolls over time.

This article is available in French on Middle East Eye French edition.