[2] Prior to joining the Department of Justice, he served as a prosecutor in the U.S. Army Judge Advocate General's Corps, as an attorney in the Professional Liability & Financial Crimes Section of the Federal Deposit Insurance Corporation, and as an associate in the law firms Fulbright & Jaworski and Kane, Russell, Coleman & Logan, PC.

Joseph previously served as an assistant United States attorney for the Western District of Louisiana, where he prosecuted a wide variety of offenses, with a focus on fraud, public corruption, white-collar crime, and crimes committed on the district's military installations.

[2] On February 16, 2018, President Trump announced Joseph as the nominee to be United States Attorney for the Western District of Louisiana.

President Trump nominated Joseph to the seat vacated by Judge Dee D. Drell, who assumed senior status on November 30, 2017.

[15] On January 10, 2024, he upheld the National Firearms Act as applied to silencers by saying that they are "dangerous and unusual weapons" in denying a motion to dismiss.