During her 22 years in the General Assembly, she was the chairperson for three committees: Education, Transportation, and the Democratic Caucus.
"[3] In 1982 she was a candidate for the Democratic Party nomination for governor, but lost in the primary to Knoxville mayor Randy Tyree, who lost in the general election to Republican governor Lamar Alexander.
In the 1980s, O'Brien was diagnosed with breast cancer, underwent a mastectomy, and received a silicone implant.
Subsequently, she worked to enact legislation to require health insurers to provide coverage for mammograms and later cosponsored a bill to expand women's rights to sue over defective breast implants by extending the statute of limitations for product liability lawsuits for implants.
[3] O'Brien died August 31, 2009, at the University of Tennessee Medical Center[4] in Knoxville after suffering a fall two weeks earlier at her home in Crossville.