He teaches and writes in the areas of criminal law, criminal procedure, constitutional law and legal history. Significantly, the Ninth Circuit cited his work on the history of material witness detentions in its opinion in al-Kidd v. Ashcroft for the proposition that such detentions date back to the 1840s. The Ninth Circuit, then, however, went on to conclude that the pretextual use of material witness detention has never occurred in this country. Wes Oliver spent the entire article describing how exactly the opposite of that proposition is true, and filed a brief on his own behalf urging the court to hear the case.