A previously confidential Ministry of Defence document grants British troops permission to engage in potentially illegal bombing, which has not been approved by parliament, a charity has claimed. The 2016 chief of defence staff (CDS) directive on so-called “embedded personnel”, released on Tuesday during legal proceedings, outlines exceptions where British troops working in foreign units can engage both in countries where the UK is not operational and against targets MPs have not approved. It also specifically acknowledges US troops embedded within a UK unit can operate outside UK rules of engagement, which set limits on what the British military can do. The document shows the rules regarding UK personnel embedded within US drone units were softened from an earlier (2014) version of the CDS, which limited drone operations to Afghanistan unless they had ministerial approval. The 2016 version permits UK personnel embedded within US drone units to carry out armed missions – no geographical limits are defined – with “specific approval, which may require ministerial engagement”. Jennifer Gibson, lead for extrajudicial killings at the charity Reprieve, said in her witness statement to the first-tier tribunal, which hears appeals with respect to freedom of information (FoI) requests: “This means UK embedded pilots could potentially be engaged in strike operations in areas beyond those approved by parliament, and potentially areas such as Pakistan and Yemen, where the US drone programme has come under significant criticism for being unlawful. Moreover, given the … US operates under different interpretations of the law, this raises concerns that UK embedded pilots may be involved in supporting and/or carrying out unlawful strikes.” The CDS says “US interpretation of self-defence and certain other legal obligations in respect of combat differ from ours,” including “use of cluster munitions”. It goes on to say that when US forces are embedded with a UK unit they will “generally” adhere to UK rules of engagement but “exceptions can apply and the position should be clarified with SC (service command) or MoD legal advisers in each case”. The CDS was released as part of an appeal by activist Ceri Gibbons – supported by Reprieve – against the information commissioner and MoD over refusal to release an unredacted version of the UK “targeting policy” (JSP900) requested under FoI legislation. The MoD initially provided the CDS unredacted by mistake. It asked for its return before agreeing to release it without redactions but continued to refuse to release the JSP900. Gibson says the CDS shows “US forces embedded with UK units are potentially carrying out unlawful activity using UK equipment, and with UK personnel at best watching or more likely, supporting and assisting”. The CDS also grants UK personnel permission to engage in planning of offensive operations against third countries on the basis they “do not usually meet the legal test of ‘significant support’ which might engage UK state responsibility.” Significant support is not defined. Gibson’s statement says: “It is imperative – both for the full functioning of democracy and for the protection of military men and women who may be held criminally liable for any unlawful acts they commit – that those portions of the JSP900 which deal with UK partner assistance and the use of UK territory be disclosed. There have been repeated calls for this from parliament.” She says concerns have been growing over the legal framework for the UK’s use of lethal force, citing the 2015 drone killings in Syria of British citizens Reyaad Khan and Mohammed Emwazi. In its written skeleton submissions, the MoD says the CDS shows “UK personnel will always be bound by UK law”. It adds: “However compelling the public interest might be in respect of information concerning the use of drones, or the use of force outside an international armed conflict, the disclosure of the withheld information would be damaging to the far broader capability, effectiveness and security of British forces in all defence contexts, as well as damaging security relations with our closest ally.” Judgment was reserved.