Professor Shoenberger first taught at the University of Nairobi, in Kenya from 1969 to 1971 which coincided with the opening of the new law school in Kenya.
Subsequently, he commenced teaching Constitutional Law at Loyola and soon began representing prisoners on appeals before various federal courts of appeals (primarily the Seventh Circuit) as well as on two occasions before the U.S. Supreme Court (preserving in one case a constitutional right related the Miranda, and resulting in an opinion that is among the most cited decisions of the Supreme Court (well over 18,000 citations).
In recent decades much of his publication has been in the area of Comparative Law with focus on a comparison of the jurisprudence of the European Court of Human Rights such as freedom of speech, defamation, and privacy.