During the sentencing portion of his case, mr. Wiggins elected to be sentenced by jury. His attorneys told the jury they would hear evidence about Mr. Wiggins' horrendous childhood in order to explain his actions and potentially receive a lesser sentence. However, they never presented that evidence to the jury. Mr. Wiggins later appealed his sentence, claiming his Sixth Amendment Right to Counsel had been violated because his attorneys had ineffectively presented his case to the jury.
The case worked its way to the Supreme Court, and in a 2002 decision, the majority held that "Trial counsel's failure to investigate the accused's background and to present mitigating evidence of the accused's unfortunate life history at the accused's capital-sentencing proceedings had violated the accused's right, under the Federal Constitution's Sixth Amendment, to the effective assistance of counsel, as such failure by trial had (a) fallen below the standard of reasonableness under prevailing professional norms; and (b) prejudiced the accused's defense."
The Supreme Court ended up granting Mr. Wiggins a new sentencing hearing on the grounds that defense counsel must thoroughly investigate all potential mitigating factors in a capital sentencing case in order to provide effective counsel and to avoid the possibility of prejudicing the client's case. The American Bar Association had already established that a thorough investigation and presentation of mitigating factors was the standard of practice, and the decision in Wiggins v. Smith made that standard explicitly clear.
Thanks for reading-- Max Wachtel, Ph.D.