States have wide discretion is making tax laws validity of a taxation derives from the police power of the state as per regulation
All similar property must be taxed equally = intentional and systematic unequal valuation for tax purposes is unconstitutional in the absence of a rational scheme (Sioux City)
Before, Congress could not have different taxes for different groups because this would be discrimination (Quaker City Cab) this was later overruled by Lehnhausen which allowed corporations to be taxed differently than individuals
Now, the tax only needs to be REASONABLE and to serve a PUBLIC PURPOSE in order to comply with the Equal Protection Clause of the 14th amendment.
Reasonableness of purpose only need be able to be imagined by court and does not necessarily have to be the real motive of the tax
Courts should be very deferential to legislative enactments (Lehnhausen)
Pollack v. Farmers’ Loan and Trust Co. (1985) – Court declared income taxes unconstitutional and because of this case Congress passed the 16th Amendment allowing income tax without regard to census of states
Sioux City Bridge Co. v. Dakota County (1923) – If all neighboring properties are undervalued for property tax purposes, an owner's land must also be undervalued so that his tax burden is equal to his neighbors