"According to his lawyers, Wallace -- after losing between 40 and 50 pounds -- was found this summer to have terminal liver cancer.
Chemotherapy treatment has not been effective and was suspended, according to Trenticosta, one of the attorneys for Wallace and Woodfox. He said the cancer should have been treated much earlier.
Wallace and Woodfox, who remains in prison with appeals pending in his case, "endured very restrictive conditions, including periods of 23-hour cell confinement," according to Amnesty International USA.
"Tragically, this step toward justice has come as Herman is dying from cancer with only days or hours left to live. No ruling can erase the cruel, inhuman and degrading prison conditions he endured for more than 41 years," Amnesty said Tuesday.
Trenticosta said he last saw Wallace a few weeks ago.
"There is no anger with Mr. Wallace," the lawyer said. "He is the strongest person I have had the great opportunity to represent. He is about positive thinking."
"He has claimed there was an unfair trial for 41 years and finally we have that ruling," attorney Nick Trenticosta told CNN on Tuesday night. "For him to pass on from this world with friends and family at his side is extremely important."