[10] Parker defeated incumbent Jean Brown in the Republican primary[11] and Robert H. Smith in the general election to become an associate justice on the Alabama Supreme Court in 2004 and was sworn in on January 14, 2005.
[19] He has worked with the Legislative and Executive Branches to restore court personnel positions lost during proration, increase funding for the judiciary, and obtain the creation of the first new judgeships since 2007.
[20] On January 20, 2025, Parker became the first Alabama chief justice to complete a full term (6 years) since Sonny Hornsby left the office in 1995.
[23] Parker was photographed at the funeral standing between Leonard Wilson, a board member of the Council of Conservative Citizens, and Mike Whorton, a leader with the League of the South.
[24] Parker was also criticized for attending a party in Selma commemorating the birthday of Confederate Gen. Nathan Bedford Forrest, founder of the Ku Klux Klan.
[23] The party was hosted at "Fort Dixie" by Pat and Butch Godwin, operator of Friends of Forrest Inc. and also involved with the League of the South.
The claim was criticized by legal experts (as well as Alabama Chief Justice Drayton Nabers Jr., whom Parker was then running against) because it contravenes the accepted principle of American jurisprudence that the U.S. Supreme Court has ultimate authority on matters of federal law.
[26] Retired U.S. Supreme Court Justice Sandra Day O'Connor criticized Parker's op-ed in a Wall Street Journal commentary, writing that it was an inappropriate attack on fellow judges and was at odds with the Constitution's Supremacy Clause.
[29] A longtime ally and former aide of Roy Moore, whose candidacy for United States Senate was derailed following multiple allegations of romantically pursuing teenagers while an adult,[9] he is known for his conservative views.
[31] Parker in February 2024 espoused the Seven Mountain Mandate that conservative Christians should hold dominion over the seven major aspects of life: family, religion, education, media, entertainment, business, and government.
Parker wrote a concurring opinion discussing the word "sanctity" in the Alabama Constitution provision on "the sanctity of life," a theologically based term that "God made every person in His image" and that "human life cannot be wrongfully destroyed without incurring the wrath of a holy God, who views the destruction of His image as an affront to Himself".