Born November 19, 1977, Justin was a graduate of Coronado High School in Lubbock Texas where he was given the nickname the Duke of Hurl. He pitched in Major League Baseball for the Texas Rangers and the Oakland Athletics.

Duchscherer was selected by the Boston Red Sox in the 8th round of the 1996 Major League Baseball draft out of Coronado High School in Lubbock, Texas. His high-80s fastball made him one of the hardest throwers in the area, but his velocity soon ranked as only average as he entered the minor leagues.

He continued to struggle in the low levels of the minor leagues, he was beginning to look more like a roster filler than a big-league prospect. But in 2001, he turned his career around. He went 6-3 with a 2.44 ERA in 12 starts for Double-A Trenton before being traded to the Texas Rangers. He finished the year pitching well with the Texas organization, going 4-0 for Double-A Tulsa and sporting a 2.84 ERA after his call-up to Triple-A Oklahoma.

In spring training 2002, Duchscherer was traded to the Oakland Athletics for Luis Vizcaíno. After suffering a lower back injury in 2002, Duchscherer bounced back in 2003, going 14-2 with a 3.25 ERA for Triple-A Sacramento.

In the spring of 2004, the A's chose Duchscherer over Chad Harville. Duchscherer appeared in 53 games out of the bullpen, sporting an ERA of 3.27. In 2005, he was selected to the American League All-Star team, the A's lone representative, but did not pitch in the game. He finished the year with 7 wins out of the bullpen and a 2.21 ERA as the top setup man for rookie closer Huston Street.

For the 2008 season, Duchscherer returned to the starting rotation for the A's. Duchscherer spent about three weeks on the disabled list with an inflamed biceps in April. After returning to the rotation, Duchscherer was outstanding and, at one point, led the major leagues in ERA. He was selected to the 2008 MLB All Star Game.

Duchscherer missed the 2009 season due to shoulder and back injuries and a bout with clinical depression. He became a free agent following the season, rejecting the A's arbitration offer. On December 30, 2009, Duchscherer signed a one-year contract with a base salary of $2 million, with another $3.5 million with incentives with the Oakland Athletics. In his second outing of the 2010 season, Duchscherer went 7 shutout innings, defeating Seattle 4-0. He missed most of the season and became a free agent on November 2.

On January 30, 2011, Duchscherer signed a one-year deal with the Baltimore Orioles. He was released on August 2.