Texas Civil Practice and Remedies Code Sec 5.001 provides:
Sec. 5.001. RULE OF DECISION. The rule of decision in this state consists of those portions of the common law of England that are not inconsistent with the constitution or the laws of this state, the constitution of this state, and the laws of this state.

In re Evett's Appeal, 392 SW 2d 781 - Tex: Court of Civil Appeals, 4th Dist. 1965 states:
Many states, including Texas, have adopted statutes prescribing a procedure for change of name. 30 Am.Jr., Name (1941), p. 610, § 28. But it is generally held that these statutes do not abrogate the common law rule which allows a person to change his name without resort to legal procedure. They merely provide a method for recording the change.