The U.S. Senate passed a measure Tuesday aimed at ensuring that the United States never tortures detainees again.

The Senate voted 78 to 21 to approve a defence bill amendment that bans torture. It was introduced by Republican Senator John McCain of Arizona and Democratic Senator Dianne Feinstein of California.

The amendment bolsters current law and makes the U.S. Army field manual on interrogations the standard for all interrogations conducted by the U.S. government. It also gives the International Committee of the Red Cross access to every detainee held by the U.S.

Feinstein said the amendment was important because the presidential executive order banning torture could one day be lifted by a future president.

"I ask my colleagues to support this amendment and by doing so we can recommit ourselves to the fundamental precept that the U.S. does not torture — without exception and without equivocation — and ensure that the mistakes of our past are never again repeated in the future," she said.

The vote comes just months after the Senate intelligence committee released findings of a classified investigation that said the Central Intelligence Agency's harsh interrogations of al-Qaeda detainees following 9/11 were worse than previously thought.