Whip Hand Meaning

(idiomatic) An advantage over another; the dominant position.

Example: The hand in which a horse rider holds the whip.
1876, Anthony Trollope, The Prime Minister, p. 271:
  Of course I was a fool. My father has the whip hand of me, because he has money and I have none, and it was simply kicking against the pricks to speak as I did.
2014, Phillip Inman, As UK economy recovers, employers remain reluctant to increase wages, The Guardian:
  Few workers are unionised, and in the UK's increasingly flexible labour market, where it is almost impossible to quit a job and claim unemployment benefits, where zero hour contracts are still a feature and where self-employment is on the rise, employers have the whip hand.