Arbitrary: a decision based on random choice or personal whim. "Willful and unreasoning action, without consideration and regard for facts and circumstances presented . . . bad faith or failure to exercise honest judgment." -Black's Law Dictionary . For example:

A restriction is arbitrary when it bears no rational relationship to the protection, preservation, operation or purpose of the affected land. (Nahrstedt v. Lakeside Village (1994) 8 Cal.4th 361, 381.)

Capricious: subject to whim; impulsive and unpredictable.

Arbitrary and Capricious: "A willful and unreasonable action without consideration or in disregard of facts or law or without determining principle." -Black's Law Dictionary. For example:

Enforcement of the restriction must be in good faith, not arbitrary or capricious, and by procedures which are fair and uniformly applied. The framework of reference, as the court made clear, is not the  reasonableness specific to the objecting homeowner, but reasonableness as to the common interest development as a whole. (Liebler v. Point Loma Tennis Club (1995) 40 Cal.App.4th 1600, 1610.)