After Wharton's death in 1839, Harris and Pease continued the partnership, and their firm, which continued until the election of Pease to the governorship in 1853, was one of the most noteworthy in Texas. When Harris became a member of the Texas bar, the republic comprised only four judicial districts. He and Pease divided the work of their office for the sake of greater efficiency and for their own convenience; Pease remained permanently at Brazoria, while Harris attended the courts of the six counties composing their district. In this way the firm was able to practice in all of the most important cases that came before the courts and before the Supreme Court of Texas as soon as it was organized in 1840.
In 1839 Harris was elected to represent Brazoria County in the House of Representatives of the Fourth Congress, where he introduced a bill providing for the abolition of the civil, or Mexican, law and the adoption of common law as the law of the land. The bill passed despite considerable opposition on the ground that common law was not sufficiently liberal in its provisions regarding the rights of married women. This feature was incorporated five years later in the Constitution of 1945qv. Harris was appointed the first Texas state attorney general by James Pinckney Henderson in 1846 and reappointed by George T. Wood, but he resigned on October 30, 1849. He was subsequently employed as a special counsel to represent the state's interests in the United States Supreme Court in matters involving land certificates issued by the Republic of Texas and suits or actions involving the constitutionality of the republic's revenue laws. In 1854 Governor Pease appointed him to a committee of three to revise the laws of the state.
Although Harris was a staunch Democrat he disapproved of secession and regarded the Civil War as entirely unnecessary. Nevertheless, he was a strong supporter of the Confederate cause. After the Civil War he moved to Galveston and resumed his law practice in partnership with Marcus F. Mott and later with Branch T. Masterson. In 1874-75 Harris represented Matagorda, Galveston, and Brazoria counties in the Texas House of Representatives. He married Mrs. Annie Pleasants Dallam, the only daughter of Samuel Rhoads Fisher, in 1852 and later adopted her daughter. The couple had four children. Harris continued to practice law until his death, on April 1, 1887, at home in Galveston.
29° 17.588, -094° 48.721
Trinity Episcopal Cemetery