QUESTION: My understanding is that regardless of the nature of the law in question (facially discriminatory, discriminatory in purpose or effect), it is subject to a Pike balancing/undue burden test.
ANSWER: I don't think that is right. If the law discriminates against interstate commerce, then it is subject to the far more rigorous "heightened scrutiny" standard. Because this is far more demanding than the "undue burden" test, I don't think there is any need to subject a discriminatory law to the Pike test as well. If it passes the very strict test for discriminatory laws, it will (by definition) pass the less demanding test.
QUESTION: In regards to facially discriminatory laws, the level of inquiry is high, at strict scrutiny, which in turn creates the notion of "virtually invalid per se." In cases involving a law which is discriminatory in purpose or effect, the Pike balancing test is much more deferential, with a lower level of scrutiny. Is my rudimentary understanding at least partially on track?
ANSWER: Just to be clear, the "heightened scrutiny" test (non-protectionist interest, no other nondiscriminatory means) applies to ALL state or local laws that discriminate against interstate commerce, regardless of whether that discrimination is facial, in purpose, or in effect. The Pike test is essentially the lesser, less rigorous standard applicable to laws that do not discriminate against interstate commerce but nonetheless impose burdens on interstate commerce.