In August 2014 Reprieve submitted an OECD complaint against G4S to the UK OECD National Contact Point.  The complaint was lodged after G4S's US subsidiary signed a contract to provide "janitorial services" to Guantanamo Bay.  Reprieve alleged that by providing services to Guantanamo Bay G4S "may contribute to the ongoing human rights violations" at the prison for terrorism suspects.

In January 2015 the NCP released an Initial Assessment rejecting the complaint saying that "It considers that UK handling is not appropriate and recommends that the complaint is submitted to the US National Contact Point"

UK campaigners condemned the decision.  See details below along with a statement by G4S.