An Oregon school bus driver fired after he refused to remove a Confederate battle flag from his pickup truck has filed a federal lawsuit to get his job back.

The lawsuit was filed in U.S. District Court in Medford on Wednesday against First Student Inc., the school bus contractor that fired Ken Webber earlier this month.

The lawsuit claims Webber's First Amendment rights to free speech were violated, and demands he be reinstated with back pay.

Webber has said that the flag -- emblazoned with the word "Redneck" -- is an expression of his cultural identity, and in no way a statement of racism or political beliefs.

The superintendent of the Phoenix-Talent School District had demanded the flag be removed from the bus yard, which is on school property, because it violated a policy about displaying symbols that could be offensive to minorities.