In 1978, he obtained his Bachelor of Arts degree cum laude from Harvard University in Cambridge, Massachusetts.
Texas Monthly magazine in October 2012, just weeks before Hartnett left the legislature, voted him a "Super-Lawyer".
[2] In 1990, Hartnett was elected to the legislature in a politically mixed year in Texas, when the Democrat Ann W. Richards defeated Republican Clayton W. Williams Jr., for governor though early in the race Williams had garnered a large lead in public opinion polls.
Senator Phil Gramm won reelection to the second of his three terms in that office by defeating the Democrat Hugh Parmer of Fort Worth.
[3] In 2001, Phyllis Schlafly's Eagle Forum rated Hartnett 93 percent, among the higher evaluations of Texas lawmakers.
He supported legislation to establish a minimum value for registration and tax purposes when an individual sells his own used vehicle to another.
He voted against a law signed by Perry which permits corporal punishment in public schools but only with parental consent.
He voted for an amendment offered in 2011 by conservative Representative Wayne Christian, who was defeated for re-nomination in 2012, to require public colleges and universities to fund student centers that promote family and traditional values.
[3] He voted for legislation, passed 102-40 in the House and signed by Governor Perry, which authorizes a county, when determining eligibility for a "sponsored alien" under the Indigent Health Care and Treatment Act, to include in the resources of the applicant any additional incomes of their spouse and sponsor.