Israeli Mordechai Vanunu made international headlines when he blew the whistle on his own government and was tried as a traitor for it.
Vanunu had worked as a technician at Israel’s Dimona nuclear plant for eight years, mostly in a secret underground bunker. After he left Israel to travel abroad, Vanunu’s conscience and his horror of nuclear war led him to tell a journalist about the bunker and what he had seen there. Vanunu revealed that Israel was collaborating with South Africa on making nuclear weapons, despite a pledge to use atomic materials for only peaceful use. He gave the journalist dozens of photos taken inside the plant that substantiated his claims. The story and pictures were spread across the pages of British newspapers, and the illegal stockpile of as many as 200 nuclear weapons was known to the world.

Vanunu was abducted by the Israeli secret service and taken back to be tried for treason and aggravated espionage. Despite his assertions that he was a whistleblower, not a spy, Vanunu’s seven-month-long secret trial ended in a sentence of 18 years, which he is serving in solitary confinement. Vanunu was presented a Right Livelihood Award in 1987 for “self-sacrificial public service of the highest kind” and has been honored worldwide for the risks he took to stop the use of nuclear weapons.

Update:
 
Vanunu served the 18 years in prison, including more than 11 in solitary confinement. Released from prison in 2004, he ’s been subjected to a broad array of restrictions on his speech and movement. He’s been arrested several times for violations of those restrictions, one of which is that he must not give interviews to foreign journalists, and must not try to leave Israel. He says he suffered \"cruel and barbaric treatment\" at the hands of Israeli authorities while imprisoned, and continues to petition for the right to leave the country.

Keep up with Vanunu at http://www.vanunu.org/