James M. Scott in 2006. (Robert A. Reeder/The Washington Post)

James M. Scott, who represented Fairfax County in the Virginia House of Delegates for 22 years and sponsored the state’s “motor voter” law allowing people to register to vote at motor vehicle licensing centers, died April 13 at an assisted living facility in Springfield, Va. He was 78.

He had complications from Alzheimer’s disease, said his wife, Nancy Scott.

Mr. Scott, a Democrat, served on the Fairfax County Board of Supervisors for 14 years before he was elected to the legislature in 1991 — by a single vote.

On election night, officials determined that Mr. Scott’s Republican opponent, David G. Sanders, had won the seat for the 53rd District by 17 votes out of nearly 13,000 cast. After a recount six weeks later, Mr. Scott was ruled the winner, with 6,493 votes to Sanders’s 6,492. He immediately became known as “Landslide Jim.”

During more than 35 years as an elected state and local official, Mr. Scott had a liberal voting record, often highlighting issues related to affordable housing and civil rights.

James M. Scott in 2006. (Robert A. Reeder/The Washington Post)

Rep. Gerald E. Connolly (D-Va.), a former chairman of the Board of Supervisors, praised Mr. Scott in a statement as a “gentle but forceful advocate for all who feel powerless.”

Mr. Scott was perhaps best known as the primary House sponsor of Virginia’s motor voter law, which was passed in 1995. He proposed the bill after then-Gov. George Allen (R) led efforts to block implementation of the National Voter Registration Act of 1993. The new law allows residents to register to vote by mail and at motor vehicle, welfare, employment and other state offices.

In 2002, Mr. Scott sponsored the “Stand by Your Ad” bill, which required Virginia candidates for governor, lieutenant governor, attorney general and the General Assembly to appear in their advertisements and personally endorse the content. The intention was to reduce negative campaign advertising.

Mr. Scott also led a successful effort to create a new state cabinet office, secretary of technology, and helped establish the School for Conflict Analysis and Resolution at George Mason University.

Some of his other legislative proposals met with mixed success, including efforts to raise teachers’ salaries, build new schools and roads, and ban handguns from governmental offices. In 2002, he sponsored a bill that would have sealed the results of presidential elections until all polls had closed in the continental United States. The bill easily passed the House of Delegates but stalled in the Virginia Senate.

Mr. Scott was reelected 10 times before announcing his retirement in 2013. His seat in the House of Delegates is now held by Del. Marcus B. Simon (D).

James Martin Scott was born June 11, 1938, in Galax, Va., and grew up in Winchester, Va. His father sold furniture, and his mother was a secretary.

James M. Scott speaking in 2003. (Stephanie K. Kuykendal/For The Washington Post)

Mr. Scott was a 1960 graduate of the University of North Carolina at Chapel Hill, where he was a student activist. He received a master’s degree in English from UNC in 1965 and a second master’s degree, in public administration, from George Mason in 1982.

He taught at Edison High School in Fairfax County for a year before working for anti-poverty and fair-housing organizations in Fairfax.

After his election to the Board of Supervisors in 1971, Mr. Scott introduced measures to protect human rights and to support affordable housing and school-based day-care centers. He was an early proponent of making the Rev. Martin Luther King Jr.’s birthday a holiday.

“Jim had a laserlike focus on quality-of-life issues for Fairfax County residents,” Kate Hanley, a former chairwoman of the Board of Supervisors and secretary of the commonwealth, said in an interview. “Jim’s experience at the local level made him an outstanding representative at the state level.”

Mr. Scott, who worked full time as a Fairfax supervisor, resigned in 1986 to become a community affairs executive with Inova Health Systems. He retired from Inova in 2011.

Survivors include his wife of 40 years, the former Nancy Cromwell of Fairfax; two daughters, Casey Scott Laxton of the District and Mary Alice Scott of Portland, Maine; and a granddaughter.

“Jim had a saying, ‘Don’t let the perfect be the enemy of the good,’ ” Hanley said. “What that meant was that compromise is not a four-letter word.”