For the most part, the Constitution speaks in generalities. The 14th Amendment, for example, instructs the states to provide all persons the “equal protection of the laws.” But obviously, this cannot mean that states are always forbidden from treating a person differently than any other person. Children can, of course, be constitutionally barred from driving, notwithstanding the Equal Protection Clause. Thus, there is a need within our constitutional system to refine the Constitution’s abstract provisions. Otherwise, public officials and the people would not know what is permitted and what is forbidden. The process of refinement has devolved principally (although not exclusively) to the courts. It is the courts that have told us that the Equal Protection Clause permits the states to discriminate on the basis of age in issuing driver’s licenses, but ordinarily does not permit the states to treat persons differently on the basis of their race.
In distilling abstract constitutional provisions into more concrete “decision rules,” courts consider a number of factors. One important factor is the workability of the decision rules they are imposing. Are they comprehensible? Can they be applied with relative ease, predictability, and consistency? Are they in fact likely to accomplish the goals that animate them?
A recent Supreme Court decision, Cooper v. Harris, reveals serious workability issues with the decision rules governing how state legislatures must treat race and partisan interests when they engage in congressional redistricting.