 Kleinfeld is generally considered a conservative judge, in contrast with the more liberal circuit he sits on.But his background in private practice as a civil and sometimes criminal defense lawyer gives him a more libertarian bent, as evidenced in his opinion in "Calabretta v. Floyd"  and his dissent in "U.S. v. Gourde"

In 2007, a Ninth Circuit panel affirmed the class action certification in "Dukes v. Wal-Mart Stores, Inc.", a lawsuit initiated by female employees of Wal-Mart against the company for gender discrimination.Kleinfeld wrote a sharply worded dissent, saying "this case poses a considerable risk of enriching undeserving class members and counsel, but depriving thousands of women actually injured by sex discrimination of their just due."