Garris was born in Cleveland, Ohio, United States. Her undergraduate education took place at Case Western Reserve University in Cleveland, and her legal training was completed at Suffolk University Law School in Boston, Massachusetts.
Her professional life developed in Massachusetts after her legal education, where she was admitted to the bar in 1980 and later built a career in corporate law and education.
Garris earned a Bachelor of Arts from Case Western Reserve University. The university was formed in 1967 when Western Reserve University and Case Institute of Technology federated. Western Reserve College had been founded in Hudson, Ohio, in 1826, and the Case School of Applied Science had been founded in 1880; the latter adopted the name Case Institute of Technology in 1947 to reflect its growing stature in the sciences and engineering. The combined institution brought together the liberal arts and professional programs of Western Reserve with the engineering and science strengths of Case.
She later received a Juris Doctor from Suffolk University Law School, completing the degree in 1980. Suffolk was founded in 1906 by Gleason Archer as an evening law school for workers and immigrants, and it grew into a law school that has been ABA accredited since 1953. The school's Massachusetts location in downtown Boston placed it within the city's legal community, and its founding purpose was to offer legal education to people who had been excluded from it by economic or racial barriers.
Garris was admitted to the bar in Massachusetts in 1980. That year she was admitted to the Supreme Judicial Court of the Commonwealth of Massachusetts, the highest court in the state, and to the United States District Court for the District of Massachusetts, the federal trial court for the district.
For nearly 24 years, she practiced corporate law with financial institutions such as J.P. Morgan and Citicorp. J.P. Morgan is a New York-based banking and financial services firm, and Citicorp was the holding company of Citibank, a major United States banking organization.
During this period she was also a partner of Legal Staff, the legal organization with which she is documented.
Her career later turned toward education. After leaving corporate law practice, she became principal of Abundant Life Christian School.
In 1982 Garris was appointed by the governor of Massachusetts to the Board of Trustees of Roxbury Community College in Boston. Roxbury Community College was established to provide higher education opportunities for communities of color in Boston. The Massachusetts legislature approved its creation in 1968 after years of activism by Black community organizers in Roxbury, and the college opened on September 10, 1973, with 400 students.
As a public community college, Roxbury Community College is governed by a board of trustees, and the board's role was to oversee the institution's management during the college's early development.
