Prosecutors allege Mauldin had sex with his wife, Eva, in an interrogation room of the Galveston County Jail days after authorities accused him of hurting his daughter.
Mauldin's defense attorney denied the accusation and said testing showed DNA on a chair in the room belonged to someone else. During a hearing Monday, attorney Sam Cammack III also said the allegation was legally inadmissible and would unfairly prejudice the jury.
State District Court Judge Susan Criss asked lawyers in the case to prepare arguments on whether the jury should know about the alleged sex act.
Mauldin's wife has refused to return from Arkansas to testify and cannot be questioned about the accusation. The defense served Eva Marie Mauldin with a subpoena but the Texas subpoena is not valid in Arkansas, Cammack said.
Mauldin told police that he brought his family to Galveston last year because he was called to preach.
Investigators say Mauldin told them he placed his daughter in a microwave oven at the La Quinta motel, as well as in the hotel room safe and refrigerator.
Ana required at least two skin grafts after suffering burns on her face and left hand.
Mauldin's parental rights were terminated and his daughter was placed with relatives in Brazos County.
Jury selection in the case was expected to begin Wednesday.