Plaintiff Betty Dukes talks to the media on the steps of the Supreme Court after the class-action lawsuit Dukes v. Wal-Mart was argued in 2011. (Larry Downing/Reuters)

Betty Dukes, a Wal-Mart greeter who took the retail giant all the way to the Supreme Court in the largest gender bias class-action lawsuit in U.S. history, died July 10 at her home in Antioch, Calif. She was 67.

Her niece Rita Roland confirmed the death but did not provide a cause.

As the lead plaintiff in Dukes v. Wal-Mart, Ms. Dukes alleged in the 2001 lawsuit that the company violated the 1964 Civil Rights Act, which made it illegal for employers to discriminate on the basis of race, creed or gender.

Ms. Dukes said Wal-Mart systemically paid women less than male counterparts and promoted men to higher positions at faster rates than women. In 2011 the case reached the Supreme Court, where it was dismissed on the grounds that the plaintiffs “did not suffer from a common policy of discrimination,” The Washington Post reported.

“Because respondents provide no convincing proof of a companywide discriminatory pay and promotion policy, we have concluded that they have not established the existence of any common question” necessary for a class-action suit, Justice Antonin Scalia said in the 5-to-4 opinion.

Betty Dukes testifies on Capitol Hill in 2011 during a Senate Judiciary Committee hearing to examine the factors at issue in the Dukes v. Wal-Mart ruling. (J. Scott Applewhite/AP)

Ms. Dukes was born in Louisiana in 1950 and moved west at a young age with her mother, who was in search of work. She later married but had no children. In 1994 she enthusiastically accepted an offer to work the Wal-Mart cash registers part time for $5 an hour. She dreamed of turning around a hard life by advancing, through work and determination, into Wal-Mart corporate management.

“I was focused on Wal-Mart’s aggressive customer service,” Ms. Dukes said in 2011 interview during her lunch break, after first saying grace over a meal of fast-food hamburgers and chicken nuggets. “I wanted to advance. I wanted to make that money.”

When Ms. Dukes needed change to make a small purchase during her break, she asked a colleague to open a cash register with a one-cent transaction, which she claimed was a common practice.

She was demoted for misconduct. She complained to a manager that the punishment was too severe and part of a long campaign of discrimination that began almost as soon as she started working for Wal-Mart in Pittsburg, Calif., a blue-collar city of about 100,000, about 45 miles east of San Francisco.

When those complaints were ignored, Ms. Dukes sought legal advice and ended up serving as the lead plaintiff in what would become the vast class-action suit.

Ms. Dukes, who worked for Wal-Mart until last year, was an ordained minister. In her off time, she helped organize community banquets with speakers celebrating Martin Luther King Jr. Day and Black History Month. She also helped distribute food to the needy.