A University of Michigan professor says he had no idea he'd given his 7-year-old son alcoholic lemonade at a ball game, and is furious at child-protection officials for removing his son from the home.

Christopher Ratte of Ann Arbor and his wife have filed a complaint against Child Protective Services.

Their son Leo spent two days in state custody. The father spent nearly a week outside his home before he was allowed to return.

He tells the Detroit Free Press that he'd taken his son to a Detroit Tigers game a few weeks ago. He didn't notice the $7 lemonade he bought contained alcohol.

A security guard noticed the boy drinking the spiked lemonade and called authorities. Leo was checked at a hospital. No trace of alcohol was found in his blood.

No charges were filed against the father, who says it was a case of "massive overreaction."