He is the author of an important article on the Privileges or Immunities Clause.

In recent years, the privileges or immunities clause has been championed by legal scholars across the ideological spectrum, for different if convergent reasons.

It was the first to locate the right to travel in the privileges and immunities clause, providing the right with a specific guarantee of constitutional protection.

However, Black's position on the Privileges or Immunities Clause fell one vote short of a majority in the Adamson case.

Legal scholars disagree about the precise meaning of the Privileges or Immunities Clause, although there are some aspects that are less controversial than others.

Another redundancy issue is posed by an interpretation of the Privileges or Immunities Clause that views it as simply a guarantee of equality.

It is far from clear to what extent the Justices are prepared to take the revival of the privileges or immunities clause beyond the context of interstate travel.

William Van Alstyne has characterized the coverage of the Privileges or Immunities Clause this way:

The privileges and immunities clauses (Article IV and Fourteenth Amendment)

For example, some substantive due process liberties may be protectable according to the original meaning of the Privileges or Immunities Clause of the Fourteenth Amendment.