The US Supreme Court has declined - for the time being - to hear the case of Joe Kennedy, who previously taught American football at Bremerton High School near Seattle.
He had filed a lawsuit with the court last summer under the First Amendment - which protects freedom of religious expression.
Kennedy is no longer working for the school after a decision was taken not to renew his contract. He was previously placed on leave in 2015.
Lower courts rejected his claim that the school district compromised his right to free speech.
COACH'S FIGHT IS FAR FROM OVER // #SupremeCourt wants more info in order to protect Coach Joe Kennedy's right to private religious expression without fear of getting fired. Find out what happens next: https://t.co/AiSH6JsIGU #TeamKennedy #SCOTUS pic.twitter.com/EIh6hstlI8— First Liberty (@1stLiberty) January 22, 2019
Bremerton School District had argued it has the right to insist that staff do not encourage or discourage religious activities related to school activities.
While rejecting the case, four of the justices at the Supreme Court said they were interested in the issues it raised. They also expressed concern over the way lower courts had handled proceedings.
Speaking with Fox News in 2017, Kennedy denied that leading prayers on playing field after matches risked alienating people.
He said: "That was never an issue; if the kids wanted to come up [to pray] they did, if they didn't, if they didn't.
"These are smart kids, and they don't feel left out of anything, they were part of our team and I was just honoured to serve them."
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