D has distributed a newsletter in its monthly billing envelope. In 1980, Toward Utility Rate Normalization (TURN) (P1), an intervenor in a ratemaking proceeding before P urged P to forbid appellant to use the billing envelopes to distribute political editorials, on the ground that appellant's customers should not bear the expense of appellant's own political speech. P decided that the envelope space was the property of the ratepayers. P then permitted P1 to use the 'extra space' four times a year for the next two years. D appealed P's order to the California Supreme Court, arguing that it has a First Amendment right not to help spread a message with which it disagrees. The California Supreme Court denied discretionary review. The Supreme Court granted certiorari.