Former Supreme Court Justice John Paul Stevens revealed he stepped down from the high court because he suffered a mini-stroke the day he delivered his dissent in the Citizens United case.

The 98-year-old writes in his forthcoming memoir, “The Making of a Justice: My First 94 Years,” that the incident caused him to stumble over and mispronounce several words during the dissent, according to the New York Times.

“Unbeknownst to me, I apparently had suffered a mini-stroke,” he writes.

"That was it," he told the Times. "I made the decision that day. After I went to see the doctor, I sent a letter to the president right away."

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Stevens dissented from the landmark campaign finance case in 2010, which eased restrictions on election spending. Months after Stevens broke with the majority’s ruling, he announced he’d be retiring, giving then-President Barack Obama his second Supreme Court vacancy.

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