Definition of cover one's back in English:

cover one's back

(North American cover one's ass)

phrase

informal
  • Foresee and avoid the possibility of attack or criticism.

    ‘never take chances, always cover your back’
    • ‘All along he has said he is acting on the advice of the Army Board, and I think he is just covering his back.’
    • ‘If that's not the sign of a man covering his ass, I don't know what is.’
    • ‘The politics of precaution, of covering your back rather than putting forward daring ideas, would dominate.’
    • ‘He is positioning himself for the leadership battle, and covering his back by allying with the obvious successor.’
    • ‘Young people should realize that he will not hesitate to put their lives on the line to cover his ass.’
    • ‘If Ashcroft was sane, he'd realize it's time to cover his ass by farming this out.’