What illinois policy did the supreme court invalidate with its decision in witherspoon v. illinois (1968) ?

A state statute in Illinois allowed for a juror to be dismissed from a case if he or she objected to capital punishment, which is a judicial term that means the death penalty. The Supreme Court found not constitutional basis for the Illinois decision to allow a jury member to be excused in the the murder case, in which Witherspoon was convicted of murder.