Unfortunately, civility is hard to codify or legislate, but you know it when you see it. It’s possible to disagree without being disagreeable.

Sandra Day O'Connor (b. 1930) American attorney, politician, Supreme Court justice (1981-2006)

Speech, Wake Forest University, North Carolina (3 Apr 1993)
    (Source)

At the dedication of the Worrell Professional Center. Quoted in "Justice O'Connor Criticizes Lawyers for 'Rambo' Tactics," Washington Post (4 Apr 1993).