He was managing partner at Hazel & Thomas in Alexandria, Virginia from 1987 to 1998, and back in Washington, D.C., from 1998 to 2008 ending as chair of the litigation department of Miller & Chevalier.
[5] In October 2009, Trenga set aside the jury conviction of two top salespeople at Teach Me to Trade, a part of Whitney Information Network,[6] which uses infomercials and hotel seminars across the country to sell courses and software on making money in the stock market.
In a 51-page ruling, Trenga said prosecutors failed to show Utah residents Linda Woolf and David Gengler had been part of any fraud scheme.
[7] On March 24, 2017, Trenga was the first federal judge to rule in favor of the Trump administration's executive order that limits travel from six Muslim-majority countries.
[9] On September 24, 2019, Trenga set aside the conviction of Bijan Khan, business partner of Donald Trump's former National Security Advisor Michael Flynn, on acting as an agent for a foreign power without notifying the Justice Department.