over a barrel
(idiomatic) In a disadvantageous or helpless situation, especially one in which one may be controlled or victimized.
We must proceed with our own energy development. Exploitation of domestic petroleum and natural gas potentialities, along with nuclear, solar, geothermal, and non-fossil fuels is vital. We will never again permit any foreign nation to have Uncle Sam over a barrel of oil. Gerald Ford
Simon Monjack had nothing to do with 'Factory Girl.' He filed a frivolous lawsuit against us... making bogus claims that we had stolen his script. He held us literally to hostage and we were forced to settle with him as he held our production over a barrel. George Hickenlooper