The three men are all described as "moderate" Sunni clerics: wad al-Qarni, a Sunni preacher, academic and author; Ali al-Omari, a popular broadcaster; and Sheikh Salman al-Odah, all of whom were arrested in September 2017.
Al-Odah, known for his critisism of the government, was given 37 charges of terrorism including affiliation with the Muslim Brotherhood, a Sunni Islamist movement. The Brotherhood was declared a terrorist organisation in 2014 by Saudi Crown Prince Mohammed bin Salman.
Last month, Saudi Arabia executed 37 people. According to the Saudi Arabian Interior Ministry, as cited by Saudi Press Agency, the individuals were charged with forming terrorist cells, adopting terrorist ideology, attacking security officers, using explosives and incitement to sectarian strife.
According to Human Rights Watch, Saudi Arabia executed 139 people in 2018 based on the interior ministry's statements. Most of the executions were for murder and drug charges.