Prior to joining his longtime friend, Rick Daly, to establish Daly & Black, P.C, John served as a legal intern to Justice James A. Baker of the Supreme Court of Texas in 1998. John worked at Gibbs & Bruns LLP, one of the nation's ​premier commercial litigation boutiques from 1999 to 2009; he was named partner in 2005. H e is flue nt in both English and Spanish with much of his family still residing in Mexico. In 2009, John left Gibbs & Bruns L.L.P. to form Reynolds, Frizzell, Black, Doyle, Allen & Oldham, L.L.P.

In his first year of helping launch Reynolds, Frizzell, Black, Doyle, Allen & Oldham, LLP, John and his partner Jean C. Frizzell secured the 12th largest verdict in Texas for 2010 (also listed 1st in corporate verdicts) and the top Texas civil practice verdict for 2010. In 2014, John joined with Richard Daly to form Daly & Black, P.C.