After graduation from law school, Leigh joined a small association of trial attorneys in Fort Worth. These attorneys focused on criminal, civil, and tort litigation. He jumped right in trying criminal and civil cases before judges and juries. During this time he also developed a niche practice doing legal research and writing for other attorneys. This developed into his own post-trial appellate and post-conviction writ practice. 

Today, he devotes his practice to criminal trials, appeals, and post-conviction writs of habeas corpus in cases with long-term, life-changing consequences.