Born in Sharon, Pennsylvania, Boyle graduated from the University of Texas with her Bachelor of Science degree in 1977 and later from Dedman School of Law at Southern Methodist University with a Juris Doctor in 1981.
Boyle was a misdemeanor and felony prosecutor in the Dallas County District Attorney's Office from 1981 to 1985 and was a chief felony prosecutor from 1985 to 1987.
She served as a United States magistrate judge of the Northern District of Texas from 1990 to 2002.
In 2002, Boyle became the United States Attorney for the Northern District of Texas until her appointment as a federal judge in 2004.
On November 24, 2003, Boyle was nominated to serve as a United States district judge of the United States District Court for the Northern District of Texas by President George W. Bush, to a seat vacated by Judge Jerry Buchmeyer.