Montreal's irrepressible lefthander, Bill Lee, drew unexpected support (out of left field?) yesterday in his grievance that Commissioner Bowie Kuhn tried to "suppress" his rights in fining him for remarks made during spring training: The American Civil Liberties Union charged Kuhn with violating the First Amendment.

The ACLU lent its support to the Major League Players Association in representing Lee in his free speech case against the commissioner. Kuhn fined Lee $250 in the spring and gagged him on the subject after Lee told reporters he had used marijuana since 1968. Lee showed up in New York for a news conference with ACLU officials, one of whom said, "Detrimental to baseball' (Juhn's operative phase) is a pretty amorphous phrase . . . "

The Major League Umpires Association is in there swinging, and no kidding: the umps filed unfair labor practice charges against the National League yesterday. Association counsel Richie Phillips met with National Labor Relations Board representatives in Philadelphia for six hours and charged the NL with five counts of discrimination against the union umpires, who staged a seven-week strike (against both leagues) at the start of the current season. The association charges that the replacement umpires who worked during the strike were given preferential treatment in the areas of guaranteed pay, advancement, vacation time, ability evaluations and expense money . . .