A Communications Interdiction, frequently shortened to Interdiction, refers to the Exclusion of a person, town, planet or state from access to the services of ComStar for committing (real or perceived) offenses against the Order. Just as its monopoly control of the hyperpulse generator network is its most important tool, denying access to it is ComStar's most powerful weapon.
Only the Primus and the First Circuit of ComStar can order or rescind an interdiction. The cause and reasons for the Interdiction are announced and broadcast to all active HPG stations throughout the Inner Sphere, after which ComStar staff in the station of the Interdicted planet/state selectively cripple the hyperpulse generator by removing specific circuit boards. The staff then go into hiding before being evacuated off-planet. The Interdiction would remain in effect until the offending realm or party agreed to ComStar's demands for compensation or repentance. For most of its existence Communication Interdictions also served as an ideal means of preserving ComStar's sanctity, giving it immeasurable power without resorting to its massive hidden stockpile of Star League Defense Force material.
Interdictions are not called lightly and the majority occurred under the reigns of the Orders most militant Primuses.
The most notable interdictions in order of occurrence are:
The Exclusion of Tharkad
- See the Exclusion of Tharkad page for more detailed information.
Long a vocal critic of the methods and motivations of the Order, Archon Richard Steiner moved a bill through the Lyran Estates General in 2823 to tax all ComStar facilities within the Lyran Commonwealth as any other business were taxed. Viewing it as an insult against the Order's neutrality, Primus Conrad Toyama responded with the Exclusion of Tharkad Act, ordering the shutdown of the HPG station on the Lyran capital until the tax act was revoked. The very first interdiction lasted a year before the Archon repealed the tax act, and the capital's position as a hub for interstellar traffic made it relatively minor compared to the interdictions that followed. 
The Exclusion of the Free Worlds League
- See the ComStar War page for more detailed information.
After receiving evidence of ComStar manipulation of the Free Worlds League, in 2837 Captain-General Charles Marik ordered the last active FWLM WarShips to obliterate the Class A HPG station and all ComStar personnel on Oriente, including his sister Jeanette Marik. Primus Toyama responded with the Exclusion of the Free Worlds League, ordering the shutdown of all HPG stations in that realm and sending their personnel into hiding until the Captain-General agree to accept blame and pay for the reconstruction of the station.
As the League and ComStar's covert divisions fought a shadow war, the other Successor States took advantage of interdiction and launched offensives against the hamstrung nation. Charles Marik resisted for almost a year, but as his internal enemies wore down his support and large swathes of League worlds were captured, he eventually sent his son under the white flag of truce to Terra. More so than the exclusion of Tharkad, the exclusion of an entire state rammed home the threat of Interdiction.
The Exclusion of the Federated Suns
- See the Fourth Succession War page for more detailed information.
Increasingly concerned by the progress of the AFFS during the Fourth Succession War and approaching formation of the Federated Commonwealth, ComStar decided to stall the Davion offensive against the Capellan Confederation in 3029. Using a Com Guard unit masquerading as part of the AFFS troops scheduled to strike at Liao held world of Sarna, ComStar publically broadcast the attack and destruction of HPG station and announced an interdiction against the Federated Suns.
While the interdiction damaged the economy and hampered the Suns military operations, the use of the so-called "fax machines", of which ComStar was unaware, allowed Davion to still capture his most important objectives. The willingness of the Order to fake the attack, a fact Davion knew due to last minute troop changes, irrecoverably damaged the relationship between the nascent Federated Commonwealth and the increasingly militant ComStar.
- See the Operation Scorpion page for more detailed information.
As the Com Guards fought the Battle of Tukayyid against the Clan invaders in May 3052, Primus Myndo Waterly put into motion her penultimate plan to "save" the Inner Sphere by placing it under total ComStar control. The opening shot of Scorpion was the complete interdiction of all HPG stations, which Waterly believed would allow ComStar forces to defeat any opposition.
While previous Interdictions had the full support of the Order, the extent of Scorpion caused a fragmentation among its members between those who saw the Order's role as the neutral protector of knowledge and those who saw the only way for the Order to protect humanity was to rule over them. Most of the Great Houses took advantage of this fragmentation to capture many of the HPG stations in their realms to try and maintain communications, while the shutdowns in the Clan Occupation Zones failed outright as the Clans eventually took control of each ComStar compounds. Scorpion was ultimately unsuccessful and the interdiction was quickly lifted.
- Dark Age: Touring the Stars (3130), p. 105
- ComStar, p. 21: "The Word of Blake"
- House Steiner (The Lyran Commonwealth), p. 58: "Tales of Grimm"
- House Steiner (The Lyran Commonwealth), p. 98: "ComStar"
- Handbook: House Steiner, p. 39: "Reconstruction"