I wouldn't accuse any of the justices of voting in voting rights cases based on a conscious calculation of what's best for the Republican or Democratic Party. But an inference of at least subconscious bias certainly fits the facts.
The Campaign Finance violations trial of John Edwards for encouraging the payment of hush money to his paramour resulted in a hung jury. Is that a helpful precedent for Michael Cohen and Donald Trump in a potential Stormy Daniels case?
Korematsu holds that in a case like this one the obligation to strictly scrutinize invidiously discriminatory policies remains even when the government asserts a facially plausible national security justification.