William M. Duncan

William M. Duncan

Yreka, California

Attorney William M. Duncan graduated from Georgetown University Law School in 1981 with honors (cum laude).   His office is located in Yreka, California (County of Siskiyou), and is diagonally across the street from the court house and thus is extremely convenient for his clients.  His practice is focused almost exclusively on criminal defense, and he has represented clients charged with nearly every conceivable crime.  This includes, but is not limited to, clients charged with murder, possession, sale and transportation of controlled substances (including medical marijuana - Prop. 215, methamphetamine, cocaine, heroin, and prescription medication), assault, battery, spousal abuse, robbery, burglary, DUI/DWI, numerous motor vehicle code violations (including driving with a suspended license, being an unlicensed driver, failure to have proof of financial responsibility, etc.) theft, rape, lewd or lascivious acts, other sex crimes, arson, forgery, and felon in possession of a firearm.

Mr. Duncan has also represented on appeal well over one hundred persons who were represented at trial by other counsel. The majority of those appeals were filed in either the Court of Appeal located in Los Angeles or in Sacramento (Siskiyou County is located within the area governed by the Court of Appeal is Sacramento), and he has obtained several reversals.  Articles concerning his representation of clients have been published in the Wall Street Journal, San Francisco Chronicle, The Recorder (state wide daily legal newspaper), and the Siskiyou Daily News. (Several of these news articles are available to view on this website by clicking this News link or the News Articles link on the menu above.)

If you have been arrested for DUI, please click this DUI link for information about representation and the possible consequences of a DUI conviction. He has handled hundreds of DUI cases involving DUIs due to alcohol and prescription drugs, as well as due to other controlled substances.

In the mid-1980's, Mr. Duncan was a trial attorney for the U.S. Department of Justice in San Francisco. He has tried cases in federal and/or state courts in Florida, New Jersey, Texas, Maryland, Missouri, Georgia, Hawaii, and California. He is admitted to practice in federal court for the Eastern District of California (Sacramento), Central District of California (Los Angeles), Northern District of California (San Francisco), and the Southern District of California (San Diego), and he is also admitted to the Ninth Circuit Court of Appeal and to the Court of Appeals for the District of Columbia, as well to the federal district court for the District of Columbia. Early in his career, he was a Coast Guard Officer and he was the officer/attorney-in-charge of representing all Coastguardsmen facing court-martial on the West Coast, Alaska, and Hawaii, and he had several criminal defense lawyers working under his supervision.

Mr. Duncan is an active member of both the State Bar of California and the Bar for the District of Columbia, and he is a member of the Siskiyou County Bar Association, and the D.C. Bar Association.

Areas of Practice

  • 90% Criminal Law
  • 10% Civil Litigation

Litigation Percentage

  • 100% of Practice Devoted to Litigation

Bar Admissions

  • California, 1987
  • U.S. District Court Eastern District of California, 1985
  • U.S. District Court Central District of California
  • U.S. District Court Northern District of California, 1985
  • U.S. District Court Southern District of California
  • U.S. District Court of the District of Columbia
  • District of Columbia Court of Appeals
  • U.S. Court of Appeals 9th Circuit, 1986
  • U.S. Supreme Court


  • Georgetown University Law Center, Washington, District of Columbia
    • J.D. - 1981
    • Honors: With Honors
  • Oklahoma State University, Stillwater, Oklahoma
    • Master's Degree cum laude - 1968
    • Major: Mathematics
  • Truman State University, Kirksville, Missouri
    • B.S. cum laude
    • Major: Mathematics

Professional Associations and Memberships

  • Siskiyou County Bar Association, Member, 1997 - 2008
  • District of Columbia Bar Association, Member
  • California State Bar Association, Member

Past Employment Positions

  • U.S. Coast Guard, Attorney, 1981 - 1988
  • Morrison Mahoney & Miller, Partner, 1994 - 1997