One day following the Galactic Empire's establishment, Imperial Intelligence apprehended sixty-three Imperial senators accused of treason and conspiracy. The Delegation of 2,000, a group of senators who unsuccessfully attempted to curb the expanding powers of Supreme Chancellor Sheev Palpatine during the Clone Wars, comprised all those taken into custody. The state-controlled HoloNet News covered these arrests, hailing them as a "remarkable triumph over the Jedi rebellion."
As the Clone Wars between the Galactic Republic and the Confederacy of Independent Systems neared their conclusion in the year 19 BBY, Sheev Palpatine, the Republic's Supreme Chancellor—secretly the Sith Lord Darth Sidious—continued to accumulate emergency powers granted by the Galactic Senate. Former senators from the Loyalist Committee, concerned about the Chancellor's growing control, then formed the Delegation of 2,000 to challenge Palpatine's increasing political dominance. This delegation authored the Petition of 2,000, a formal objection to Palpatine's political gains and an effort to restore emergency powers to the Senate once the war ended.
Palpatine ultimately dispatched his Sith apprentice, Darth Vader, to the planet Mustafar with orders to annihilate the Executive Separatist Council and deactivate the Separatist Droid Army, effectively bringing the Clone Wars to a close. Simultaneously, before a session of the Senate, the Chancellor denounced the Jedi, the Republic's protectors, as traitors, revealing the thwarting of an alleged Jedi rebellion. Capitalizing on widespread public support, Palpatine seized the opportunity to declare the Republic's transformation into the first Galactic Empire, with himself as Emperor—though figures like Bail Organa and Padmé Amidala watched with dismay.
A day after the Empire's establishment, Imperial Intelligence, the state's intelligence and anti-sedition agency, initiated a crackdown on Palpatine's political adversaries on Coruscant, executing a mass arrest of sixty-three senators—all of whom had signed the Petition of 2,000—on charges of conspiracy and treason. The arrested included senators from prominent Core Worlds as well as numerous alien senators hailing from the Outer Rim Territories. Senators Mon Mothma and Bail Organa were temporarily detained but subsequently released after affirming their allegiance to the Empire. The apprehended senators were transported via a Theta-class shuttle under the guard of Imperial clone troopers. Following the initial wave of arrests, Senator Tanner Cadaman was arrested within days, while Senator Ivor Drake was apprehended shortly after Padmé Amidala's funeral.
In the wake of the arrests, HoloNet News, the Empire's official state-approved news source, reported on the events, characterizing them as a "dramatic victory over the Jedi rebellion." Prior to publication, a partial list of those arrested was released, identifying Senators Shea Sadashassa of Herdessa, Ivor Drake of Kestos Minor, Fang Zar of Sern Prime, Streamdrinker of Tynna, and Tanner Cadaman of Feenix as being among those taken into custody. Nee Alavar was also arrested, but disappeared soon after.
Sadashassa, Drake, and Cadaman were ultimately imprisoned at the Arrth-Eno Prison Complex on Coruscant. Drake resisted pressure to identify his allies. They were killed there shortly following the Battle of Yavin, which occurred when a Rebel Alliance operation to murder Palpatine and liberate imprisoned senators sympathetic to the Rebellion went wrong.
Bail, concerned for his daughter Leia's safety when she joined the Rebel Alliance, warned her about Palpatine by recounting the arrests. Leia later documented her father's account in her personal writings, Lessons from serving in Palpatine's Senate, during the New Republic Era.
The Rebel Files, a secure, non-digital repository of sensitive rebel information, included Mon Mothma's recollections of the arrests, detailing how she and Bail avoided arrest by declaring their loyalty to the Empire. Mothma explained that her resulting guilt motivated her to continue secretly opposing the Emperor and developing the Rebel Alliance.
In 35 ABY, Beaumont Kin, a historian, authored and published The Rise and Fall of the Galactic Empire, a book chronicling the Empire's ascent and demise. In the book's opening chapter, "Emperor Palpatine," Kin referenced the senatorial arrests, citing Leia's writings as a source.
The senatorial arrests were first mentioned in current Star Wars canon in Star Wars: The Rebel Files, a 2017 reference book by Daniel Wallace. The event originated in the Star Wars Legends article "Republic HoloNet News Special Inaugural Edition 16:5:241," which was co-written by Wallace and Pablo Hidalgo for the eighty-fourth edition of the Star Wars Insider magazine on September 26, 2005.