Now she is a Baltimore Circuit Court judge, and a ruling last week has thrust her into another equal rights issue - this one a particularly contentious battle playing out at a national level.
The judge ordered the law be overturned, but she stayed her order pending an appeal, which was immediately filed by the state attorney general's office.
Murdock's ruling comes at a time when courts and legislative bodies in several states are taking a look at the divisive issue of same-sex marriage, and it drew immediate praise and condemnation from varied groups, including Westboro Baptist Church in Topeka, Kan., which called Murdock "antichristic."
Murdock, 56, was not at work yesterday, and she did not return phone calls. Her friends and those who have worked with her say that while she shies away from the spotlight, she has built a reputation as a passionate protector with a keen focus on equality.
She based her ruling on the theory that the law discriminates on the basis of gender, writing that, for example, a woman can marry a man, but Maryland prevents another man from exercising that right.
"Having concluded that preventing same-sex marriage has no rational relationship to any other legitimate state interest, this Court concludes that tradition and social values alone cannot support adequately a discriminatory statutory classification," Murdock wrote in her 20-page opinion.
Fred Warren Bennett, who hired Murdock in 1987 as an assistant federal public defender, said he was not surprised by Murdock's ruling because, he said, "I do not perceive her to be a very conservative judge. She called it as she saw it."
Bennett said Murdock would not be one to pay attention to the rhetoric of groups for and against same-sex marriage.
"She wouldn't worry about what the left or right side might write," he said.
Bennett said Murdock was "a tiger in the courtroom" as a lawyer for nearly two decades and has continued to be a "fair and balanced person" as a judge.
Murdock, a Baltimore native, has been on the bench since Gov. Parris N. Glendening appointed her in 1997. She is a graduate of the University of Delaware and received her law degree from the University of Baltimore in 1977.
In one of her most memorable rulings as a Circuit Court judge, Murdock decided in July 2004 that Gov. Robert L. Ehrlich Jr.'s administration acted unlawfully when it appointed the head of the city-based social service agency over the objections of Mayor Martin O'Malley.
While Murdock was judge in charge of petit jurors from 1999 to 2003, she tried to chip away at the city's no-show juror problem by occasionally calling habitual offenders to a special hearing and fining them as much as $700.
Murdock began her legal career in 1978 as a city prosecutor, and she worked for four years as a federal public defender before going into private practice. With three other attorneys, Murdock founded a law firm in 1996.
"She was a real fighter for the rights of individuals against the state," said Thomas J. Schetelich, a former law partner of Murdock's, speaking about her time as a criminal defense attorney. "She championed the people she represented and took cases very much to heart."
Another of her former partners, Robert L. Ferguson Jr., said Murdock has always been "passionate about the law and passionate about her profession."
"She was a well-prepared and skillful lawyer," he said.
Along the way, Murdock joined several women's law organizations, such as the law center in Towson, the Women's Bar Association and the National Association of Women Judges. She was president of the law center from 1995 to 1996 and had served on its board since 1991.
Murdock was selected in 2001 for the Daily Record's "Circle of Excellence," meaning the newspaper had thrice placed Murdock on its "Maryland's Top 100 Women" list.
She owns a house in Federal Hill and told The Daily Record in 2001 that she has enjoyed traveling to Europe and North Africa. "My life is enriched by travel," she told the newspaper. She also said she collects local art and participates in a classics book club. She has been involved with the Walters Art Museum and Baltimore Clayworks, a nonprofit ceramics art center.
Bennett said Murdock has told him she is happy being a judge. Ferguson said his former colleague has told him she enjoys the job but finds it "a heavy responsibility.
"She works very hard to live up to those demands," he said.