Salem and Waleed were both opponents of al Qaeda in Yemen. Salem was a local Imam who five days before he was killed had been preaching against the terrorist group and Waleed was a local policeman. Mr Jaber is seeking only an apology from the US government.

In June this year the US Court of Appeals for the District of Columbia said it did not have the authority to decide whether the drone strikes that killed the two were legal. However, in a concurring opinion, Judge Janice Rogers Brown attacked the system of accountability for lethal action taken by the President, stating “our democracy is broken” and “congressional oversight is a joke – and a bad one at that.”

A report by Reprieve into the drone programme in Yemen, launched alongside the CrowdJustice campaign, reveals a five-fold increase in the rate of drone strikes in Yemen since President Trump took office in January and evidence of civilians being recklessly killed.

Reprieve is now assisting Mr Jaber to take his case to the Supreme Court to ensure that the power of the President to take potentially lethal action against civilians is subject to proper checks and balances.

Shelby Sullivan-Bennis, an attorney at Reprieve US said: “Faisal is seeking justice for his innocent relatives, but this case is also about the accountability of the President to Congress and the people for lethal decisions he takes in their name. Judge Brown accurately labelled the current system of oversight ‘a joke’, but she felt her hands were tied. Now the country’s highest court should have the opportunity to ensure there are proper checks on the power of a President who has shown little regard for civilian life.”