Emeritus Professor Forrest is both an attorney and planner. He has been in private practice and served as Assistant Director of the Office of Urban and Community Planning, University of Oklahoma and their Model Cities Program. From 1959 to 1962 he was a planner and legal coordinator for the Tulsa Metropolitan Area Planning Commission.
Recognized as an expert on state and local land use, zoning, and subdivision law, he has written model legislation for the State of Illinois; consulted with federal, state, and local governments; and led public service and continuing education programs in planning and environmental law. Current research includes studies of groundwater, federal environmental regulation, and land-use controls in relation to the taking issue.
Professor Forrest served as Director of the Illinois General Assembly's Land Resources Study Commission. He is the Vice Chair of the APA Divisions Council and Past Chair of the Environmental, Natural Resources and Energy Division of the American Planning Association.