In the case of Saffle v. Parks, 1990, the U.S. Supreme Court ruled that a jury instruction given during Robert Allen Parks' sentencing phase did not violate his Eighth Amendment rights. The instruction in question asked jurors to avoid being swayed by "mere sentiment, conjecture, sympathy, passion, prejudice or public opinion." Parks argued this violated his right against cruel and unusual punishment as it prevented him from presenting mitigating evidence about his character and background for consideration of leniency in sentencing. However, the court held that while defendants are allowed to present such evidence under Lockett v Ohio (1978), there is no constitutional requirement for juries to consider them when deciding between life imprisonment or death penalty sentences.

In the dissenting opinion for Saffle v. Parks, Justice Blackmun argued that the majority's decision was too broad and failed to consider important nuances of the case. He disagreed with their interpretation of Teague v. Lane, arguing that they had misapplied its principles in this context. Specifically, he believed that Parks' claim did not represent a "new rule" as defined by Teague but rather an application of existing precedent to a new set of facts - namely, Oklahoma's jury instruction requiring jurors to avoid any influence from sympathy when deciding on sentencing in capital cases. In his view, this instruction violated Eighth Amendment protections against cruel and unusual punishment because it prevented consideration of mitigating factors which could lead to lesser sentences than death penalty.