Jack Shapiro was the highest ranking Watcher in Europe, and head of the Tribunal, at the beginning of the episode Judgement Day. He was the father of Watcher, David Shapiro. He organized a plot to take Joe Dawson into custody by telling him Duncan MacLeod was dead, and Joe had to complete a terminal report at Watcher HQ. The tribunal decided Joe had broken his oath by consorting with an Immortal, which they believed resulted in the deaths of over 80 Watchers over the previous two years.
During a kangaroo trial, Jack presided, brushing aside testimony from researcher Adam Pierson, and from an Immortal, Duncan MacLeod. At trial's end, he learned that David had been murdered by an Immortal and blamed Dawson and MacLeod for his death, despite there not being any clear evidence. On the morning of Dawson's scheduled execution, he left the headquarters unable to watch the sentence he had supported be carried out, and so escaped the massacre perpetrated by Jacob Galati, which resulted in the deaths of a dozen high-ranking Watchers. When MacLeod appeared after the fact, and spirited the badly wounded Dawson away, Shapiro, once more without any clear evidence, accused MacLeod and Dawson of the Watcher deaths, and spearheaded a massive manhunt for both fugitives, re-tasking the entire Watcher network to hunt for the pair, in a massive breach of Watcher ethics and laws.
After Jacob Galati was discovered as the true killer of the Watchers, Shapiro used Dawson to bring Jacob to him, promising a parley. But when Duncan and Joe brought Jacob in, Shapiro pulled out a sword and killed a gloating Jacob. Upon his death, MacLeod, surrounded by armed Watchers; received Jacob's Quickening. Once again violating his oath, Shapiro attacked Duncan, but was stopped by Dawson, who threatened to shoot him.
Full of grief over the loss of his son, Jack prepared the Watchers for a full-scale war against Immortals to avenge David, a gross violation of his oath, and a disturbing throw back to the Hunters work of the late James Horton. No longer caring about the oath he took, refusing to listen to Dawson, and throwing him out of the Watchers, he was met at gunpoint by MacLeod. Dawson begged both men to let it end, and MacLeod demanded a decision from Shapiro, the death of more Watchers or peace. Terrified for his own life, Shapiro agreed to rescind the orders that would launch an all out war between Watcher and Immortal. MacLeod confined Shapiro in a casket, and told him the killing ended right there, or he would be back for him.
Following the events of One Minute to Midnight, Jack was tried by the Watchers for violating his oath, and nearly plunging the organization into war. He was forced to leave the Watchers, but further retribution was waived as the council determined that the loss of his son was punishment enough.