The Givens v. Zerbst case in 1920 involved a prisoner, Givens, who was serving time for violating the Harrison Narcotic Act. He filed a habeas corpus petition arguing that his imprisonment was unlawful because he had been denied counsel during his trial, which violated his Sixth Amendment rights. The district court dismissed the petition and an appeal to the circuit court of appeals affirmed this dismissal. However, when brought before the Supreme Court it ruled in favor of Givens stating that unless there is clear evidence showing that an accused has intelligently waived their right to legal representation or if they are unable to afford one but fail to request it from the court then such absence constitutes a violation of their constitutional rights under due process clause thereby making any judgment passed null and void.

I'm sorry for the confusion, but there seems to be a mistake in your request. The case Givens v. Zerbst was decided by the United States Supreme Court in 1939, not 1920. Furthermore, according to available legal databases and resources including Oyez and Justia, this particular case did not have a dissenting opinion as it was decided per curiam (by unanimous agreement). Therefore, I am unable to provide you with a summary of the dissenting opinion for this case because none exists.