Does a law that is triggered by a proxy for participating in interstate commerce and that burdens out-of-state entities almost exclusively violate the dormant Commerce Clause?

QUESTION PRESENTED The State of Washington has enacted a major surtax—an increase of nearly 70%—on the gross receipts of certain financial institutions: namely, any such institution that is part of a consolidated group earning at least $1 billion in net income anywhere in the world. Before enacting the surtax, the legislature verified that no in-state bank would have to pay it, and the legislature chose a trigger for the surtax that captures only banks that do large volumes of business outside the state. The result leaves little to the imagination: 98% of financial institutions subject to the surtax have their principal places of business outside Washington State, and 99.74% of surtax revenue comes from entities based out of state. All entities paying the surtax are subject to it only because they are affiliated with extensive interstate banking networks. Nonetheless, the Washington Supreme Court upheld the surtax under the dormant Commerce Clause. In doing so, it deepened acknowledged division in the lower courts. Numerous courts have properly held that regulating on the basis of a feature that is a proxy for being based out of state, or for participating in interstate commerce, amounts to impermissible discrimination against interstate commerce. Other courts disagree. The question presented is: Does a law that is triggered by a proxy for participating in interstate commerce and that burdens outof-state entities almost exclusively violate the dormant Commerce Clause?