Exclusion of Tharkad
By 2820 Primus Conrad Toyama's purges of "disbelievers" from the Blessed Order were winding down, and Toyama embarked on a tour of the capitals of the Great Houses to meet each of the Inner Sphere leaders. While publicly the goal was to explain the new organization and structure he'd created, in reality Toyama wished to explain how he had saved the Inner Sphere from a rouge First Circuit that had sought to take over the Inner Sphere. It was due to this that Toyama had claimed that the Order needed to rebuild its damaged infrastructure and was levying an 15 percent increase in HPG transmission costs. The various leaders gave this news a cold reception, save for Archon Richard Steiner of the Lyran Commonwealth. 
Long a vocal critic of the Order, Richard now openly and repeatedly questioned the organizations motives, even hinting that he suspected Toyama planned an eventual attempt to take over the Inner Sphere. Things came to a head Richard's son Marcus, convinced the Lyran Estates-General to pass his father's Reclamation Act of 2823. The act required that ComStar's profits and property be taxed like any other business operating in the Lyran Commonwealth. Toyama knew he had to act swiftly to ram home that ComStar was not just a business, and lest any other leaders decided to follow suit.   
When the first tax bill to the Commonwealth came due, Primus Toyama persuaded the First Circuit to pass the Exclusion of Tharkad Act, which called for ComStar's first Communications Interdiction against one of the Successor States. On October 3 2823, a copy of the Act was transmitted to Tharkad and delivered to the Archon, followed by the shutdown and disabling of the capital's Hyperpulse Generator. Before the Archon could even respond, all ComStar personnel were safely evacuated off world.   
With the Lyran capital a prime stop on numerous shipping and trade routes, pony express style transfers messages to nearby worlds with still transmitting HPGs prevented a complete collapse of the function of government, but introduced increasing delays and hardship on civilian and commercial communications. The Interdiction lasted almost a full year with little communication between the Commonwealth and ComStar before Marcus eventually bowed to public pressure in the fall of 2824 and asked the Estates General to rescind the Act. Within 72 hours of the announcement, the Tharkad HPG was again active processing.   
The impact and the message of Exclusion of Tharkad were quite clear, while ComStar lacked any (public) military force and professed neutrality, it would defend itself with it's most powerful tool if threatened. While the Interdiction of Tharkad at best caused delays and annoyance for the government, the threat of what could happen if a whole Successor State lost access to ComStar's services was a powerful one, a threat which would become reality only 14 years later during the so-called ComStar War.   
- ComStar, p. 21 "A New Order - The Word of Blake"
- House Steiner (The Lyran Commonwealth), p. 58 "History - The Second Succession War - Tales of Grimm"
- House Steiner (The Lyran Commonwealth), p. 98 "Sociopolitical Structure - Interstellar Relations - ComStar"