Following graduation from the Texas Tech University School of Law in 1993, McDonald spent the next 22 years in private practice.  His private practice experience included representing clients in criminal and family matters, with an emphasis on representing citizens accused of committing criminal offenses. 

McDonald transitioned to teaching in the Criminal Defense Clinic at Texas Tech in January 2015.  He also teaches Law Office Management, Introduction to the Study of Law, and the Regional Externship class. Based on student evaluations and his innovative teaching methods, McDonald received the Texas Tech Alumni Association New Faculty Award in 2023.

In addition to his teaching duties, Professor McDonald has been active in bar activities on the local and state levels.  He currently serves on the Board of Directors for the State Bar of Texas and was on the Board of Directors for the Texas Criminal Defense Lawyers Association from 2018-2023.  He served as the Chair of the Criminal Justice Section of the State Bar of Texas in 2021 and was the President of the Lubbock County Bar Association from 2022-2023.