may a taxi corporation be taxed at a higher rate than an
1. the equal protection clause does not prevent states from
classifying for tax purposes but: "it does require that the
classification be not arbitrary but based on a real and
substantial difference having a reasonable relation to the
subject of the particular legislation."
2. Brandies Dissent: given that corporation has some advantages
over sole proprietorship, make tax more equal in real world
a. corporations have certain legal advantages
b. historically, corps have been taxed
c. policy reason: might want to discourage corps.