In the case of Andrus v. Texas, 2019, Terence Andrus was convicted for two counts of attempted capital murder and sentenced to death in Texas. The Supreme Court ruled that his defense counsel provided ineffective assistance by failing to investigate or present mitigating evidence during the penalty phase of his trial which could have potentially spared him from a death sentence. This evidence included severe childhood trauma, drug addiction issues and mental health problems including borderline intellectual functioning. The court found that had this information been presented at sentencing, there would have been reasonable probability that he would not have received a death sentence due to these substantial impairments affecting his conduct at the time of offense.

The dissenting opinion in the case of Andrus v. Texas argued that the defendant, Terence Andrus, did not receive effective assistance from his counsel during the penalty phase of his trial for capital murder. The dissent pointed out that Andrus's lawyer failed to investigate and present mitigating evidence about his client's background and mental health issues which could have potentially swayed jurors towards a sentence other than death. This failure was seen as a clear violation of established legal standards requiring defense attorneys in capital cases to conduct thorough investigations into potential mitigating factors. The dissent also criticized the majority’s application of precedent regarding prejudice resulting from ineffective assistance, arguing it set an unreasonably high bar for defendants seeking relief on these grounds.