One of the biggest surprises of the Donald Sterling mess was the the NBA's own constitution and bylaws were confidential, leaving observers to speculate on the league's mechanism for punishing the Clippers owner. Well, soon after dropping the hammer on Sterling, the NBA finally made the constitution public.
The full document is below. Though commissioner Adam Silver did not cite the rules in play in Sterling's situation, we think we can figure them out.
Article 24(l) is the big one. The "best interests of the Association" clause that essentially gives Silver the power to levy any punishment he sees fit when a violation is not specifically covered elsewhere. (It also sets the maximum amount for Sterling's fine.)
The Commissioner shall, wherever there is a rule for which no penalty is specifically fixed for violation thereof, have the authority to fix such penalty as in the Commissioner's judgment shall be in the best interests of the Association. Where a situation arises which is not covered in the Constitution and By-Laws, the Commissioner shall have the authority to make such decision, including the imposition of a penalty, as in his judgment shall be in the best interests of the Association. The penalty that may be assessed under the preceding two sentences may include, without limitation, a fine, suspension, and/or the forfeiture or assignment of draft choices. No monetary penalty fixed under this provision shall exceed $2,500,000.
Article 35A(d) (the whole subsection deals with "misconduct of persons other than players," and is a relatively new inclusion; it didn't exist in the version of the constitution we saw, which only gave the league power over players) explains Sterling's lifetime suspension for "conduct...detrimental to the Association."
The Commissioner shall have the power to suspend for a definite or indefinite period, or to impose a fine not exceeding $1,000,000, or inflict both such suspension and fine upon any person who, in his opinion, shall have been guilty of conduct prejudicial or detrimental to the Association.
Article 13(a) lays out the process for voting an owner out of the league:
The Membership of a Member or the interest of any Owner may be terminated by a vote of three fourths (3/4) of the Board of Governors if the Member or Owner shall do or suffer any of the following:
(a) Willfully violate any of the provisions of the Constitution and By-Laws, resolutions, or agreements of the Association.
Here, the full and most recent version of the NBA constitution and bylaws, written the offseason after the last lockout.