Walton's father worked two jobs in the steel town Donora, Pennsylvania. He won a football scholarship to get his Bachelor of Arts degree from West Virginia State College in 1971, and then a Juris Doctor from the Washington College of Law at American University in 1974. Walton is a member of Alpha Phi Alpha fraternity.
Walton served as an Associate Judge of the Superior Court of the District of Columbia from 1981 to 1989 and from 1991 to 2001. He also served as associate director of the Office of National Drug Control Policy. In 2001, he was nominated to the federal bench by President George W. Bush, and subsequently confirmed by the United States Senate. In 2004, Bush appointed him to chair the National Prison Rape Elimination Commission, investigating ways to curb prison rape. In May 2007, Chief Justice of the United States John G. Roberts Jr. appointed him to a seat on the Foreign Intelligence Surveillance Court. His term on the Foreign Intelligence Surveillance Court ended May 18, 2014. He assumed senior status on December 31, 2015.
During his FISC tenure, Judge Walton was "exceptionally concerned" about the NSA's "flagrant violation" of the court orders regarding privacy, and he accused the agency of "misinterpretations."
The Washington Post reported, "fellow judges and lawyers who appear before him say Walton's decisions do not appear to be guided by politics but by a tough-on-crime mentality." Walton is known by local defense attorneys as a "long ball hitter" - a judge willing to impose long sentences in order to deter future crimes. In fall 2005, the judge was driving his wife and daughter to the airport for a vacation when he came across an assailant attacking a cab driver on the side of the road. Walton tackled the assailant and subdued him until police arrived. The D.C. police spokesperson noted in response, "God bless Judge Walton. I surely wouldn't want to mess with him."
Walton also presided over the trial of Vice President Dick Cheney's former chief of staff, Scooter Libby. On March 6, 2007, the jury convicted Libby of four of the five counts with which he was charged: two counts of perjury, one of obstruction of justice, and one of making false statements to federal investigators. On June 5, 2007, Walton sentenced Libby to 30 months in federal prison and a fine of US$250,000, and, subsequently, he ordered that Libby report to jail without bail pending any appeals. On June 20, 2007, Libby appealed Walton's ruling in federal appeals court. The next day, Walton filed a 30-page expanded ruling, in which he explained his decision to deny Libby bail in more detail.
Walton received several threatening letters after pronouncing sentence on Libby.
Walton was the presiding judge in Tripoli Rocketry Association, Inc. and National Association of Rocketry v. United States Bureau of Alcohol, Tobacco, Firearms and Explosives, a long-running case brought by the two largest hobby rocketry organizations, which challenged the inclusion of certain types of solid fuel rocket propellant on the list of "explosives" regulated by the BATFE. On March 16, 2009, Walton ruled in favor of the rocketry organizations.
On August 30, 2010, USA Today reported that Walton arraigned former major-league pitcher Roger Clemens on charges of lying to Congress (three counts of making false statements, two counts of perjury, and one count of obstruction of Congress) about the use of performance-enhancing substances. Pre-trial prosecutors brought a motion of conflict of interest against defense attorney Rusty Hardin for having briefly represented Andy Pettitte, who is an important witness for the government.
On July 14, 2011 Walton declared a mistrial over inadmissible evidence shown to jurors. The judge said Clemens could not be assured a fair trial after prosecutors showed jurors evidence against his orders in the second day of testimony. Following the mistrial, the US Attorneys Office brought Clemens to trial once more for perjury. On June 18, 2012, Judge Walton accepted the jury's unanimous verdict of acquittal.
On October 4, 2016 Walton rejected the release of Hillary Clinton criminal indictment drafts prosecutors prepared, but never issued, during the Whitewater investigation in the 1990s. He ruled that Hillary had a "substantial privacy interest" when he rejected a Judicial Watch lawsuit under FoIA.
Walton presided over Mohammon v. Bush, a set of amalgamated habeas corpus petitions, submitted on behalf of Guantanamo captives.
Walton has been presiding over the lawsuit that Steven Hatfill filed against former US Attorney General John Ashcroft. Ashcroft publicly described Hatfill as a "Person of interest" in the FBI's investigations into the 2001 anthrax attacks. On March 30, 2007, Walton issued an order warning Hatfill that he may lose his civil lawsuit over the leaks if he does not compel journalists to name their sources and giving Hatfill until April 16, 2007, to decide whether to do so. Hatfill's lawyers have complied with the order, as reported on April 18 by Gerstein, who warns that a "free press battle looms," as
The reporters in jeopardy now are expected to defy Hatfill's subpoenas and any court order to name their sources. ... one critical issue will be whether Judge Walton imposes fines on the news organizations involved. ... A First Amendment battle could possibly be avoided: The government and Dr. Hatfill's lawyers asked Walton to name a mediator to explore a possible settlement of the case. ... No one has been charged in the anthrax attacks, which killed at least five people.
On August 21, 2009 Reuters reported that Walton issued a ruling about "hearsay evidence" that applied to all the Guantanamo detainees' habeas petitions before him. Much of the evidence the Department of Justice is presenting in the habeas petitions is hearsay evidence.
"Even the most widespread rumors are often inaccurate in part if not in whole. The court's only point is that otherwise unreliable hearsay cannot be deemed reliable because there is other unreliable hearsay to the same effect."