have (someone) in (one's) pocket
To have someone under one's control or influence, especially in an underhanded or unethical way, such as by bribery or extortion. It's pretty obvious that corporate bigwigs have all of our national legislators in their pockets. I hear that the boss has half the police force in his pocket.
have someone in one's pocket
Fig. to have complete control over someone. Don't worry about the mayor. She'll cooperate. I've got her in my pocket. John will do just what I tell him. I've got him and his brother in my pocket.