Holding: It was not unconstitutionally impairing on contractual right or expectation.
(1) A statute does not violate the K Clause simply because it has the effect of restricting, or even barring altogether, the performance of duties created by the Ks entered into prior to its enactment. Otherwise, you could obtain immunity from state regulation by making private contractual arrangements.
(2) The pass- through prohibition did not prescribe a rule limited in effect to contractual obligations or remedies, but instead imposed a generally applicable rule of conduct designed to advance “a broad social interest”-to protect consumers from excessive prices.
(3)    (a) Distinguished from Allied Structural Steel:
– MN statute directly adjusted the rights & responsibilities f contracting parties.
(b) Relied on Producers Transportation Co. v. Railroad Comm’n of CA (1920).
– State law authorized a state commission to set the rates of transporting oil by pipeline. Court found that a common carrier cannot bark on the state not imposing regulations on the carriers’ rates & practices.
(c) If a state can set rates charged to consumers, a state can tell producers to absorb the cost of a tax increase.