In the fictional universe of Babylon 5, the Psi Corps is an agency of the Earth Alliance responsible for all humans with telepathic or other para-psychological abilities anywhere within Earth controlled space. All persons with Psi abilities are required to either join the Corps, face lifetime imprisonment, or submit to a lifetime of drug treatments to suppress their abilities. Prolonged treatment with these drugs have a depressing effect; Susan Ivanova's mother committed suicide after ten years under treatment.
The Psi Corps headquarters has hospitals, offices and a boarding school where young "teeps" and "teeks" can develop without the fear and persecution they would face among the normal, "mundane" population. This school is overseen by the monitors (usually called by their nickname, "grins"), which appear in Susan Ivanova's nightmare about the corps and her mother. (Family names are matriarchal: the mother's maiden-name is passed down to the children, which is why female telepaths such as Lyta Alexander and Talia Winters carry their surname down the generations.)
The Corps was originally established to protect, nurture and train humans with Psi abilities, and to protect the general, un-talented population from possible abuse or criminal activities by talented individuals. At some point the Corps realized it could not be effectively monitored by any external authority and developed into a fascist state-within-a-state, pursuing its own agenda using the Psi Cops and other means, and taking an active role in Earth politics.
By the time of the pilot movie, Babylon 5: The Gathering, the Corps' has degenerated to the point where many potential and former members prefer a life on-the-run as rogue talents (referred to by the Corps as "blips") to the safety and comfort of living and working under its wing.
"Psi Cops" are members of a para-military body enforcing laws related to telepaths and operates with few checks against their authority. This is especially true when dealing with non-telepaths who have done violence against a member of the Psi Corps. For example, after capturing a murderer of telepaths, they implanted an image in his mind so horrifying that the person had to be permanently restrained to prevent him from ripping out his own eyes. In another case, a man who murdered a Psi Cop was ejected from a spaceship. While Psi Cops claim to only want to bring rogue telepaths back to the Psi Corps family, they are likely to kill a rogue telepath upon capturing one. Psi Cops possess a rating of P-12 (the highest rating within the "P-scale" used in the series to measure psionic strength) P-13's or slightly higher are a rarity and some of those that are eventually found out to be P-13's, also become rogue telepaths and go on the run in fear of what the Psi Corp will do with them through experiments (A Race Through Dark Places), Psi Corp also use telepaths of lower ratings in support roles.
Psi Corp has attempted to increase a telepath's abilities through genetic manipulations and experiments, one such experimentation produced enhanced abilities in a P-10 level telepath named Jason Ironheart, in an attempt to produce a stable telekinetics and stronger telepaths for the Psi Corp. Ironheart volunteered to have his telepathic powers increased, but they soon became unstable. He fled from Psi-Corps, eventually coming to B5 where he set up an escape route for other rogue telepaths, but was pursued by Bester. However, Ironheart began to undergo destructive "mindquakes," releasing bursts of psychokinetic energy so powerful they threatened the station. As Ironheart realized that his abilities had grown too great to contain, he discorporated his physical form, but not before leaving Talia with a gift; enhanced telepathic shields, and even a bit of telekinesis of her own (Mind War).
Doctor Stephen Franklin of Babylon 5 participated in an underground railroad to help rogue telepaths escape from the Corps (A Race Through Dark Places). Eventually, the telepaths who escaped provided assistance during the closing days of the Shadow War. Later on, President John Sheridan of the Interstellar Alliance allowed rogue telepaths to form a small colony on Babylon 5. The situation ended in violence when the Psi Cops attempted to take the rogue telepaths back to Earth.
After the colony on Babylon 5 was forced to leave following the death of its leader, Byron, Lyta Alexander began a crusade against the Psi Corps. Her actions led to a war in which rogue telepaths and non telepaths fought the Psi Corps. The old Psi Corps was destroyed, and a new Psionic Monitoring Commission was built to replace it.
Once the Telepath War was over, the Psionic Monitoring Commission dedicated itself to hunting down those members of the Corps who committed war crimes, such as Alfred Bester. He was eventually captured and sentenced to spending the rest of his life in prison with his abilities taken away by drugs. Many private schools were founded to educate telepaths; they met with mixed success. Telepaths were allowed a much wider range of options as far as their lives were concerned. Rather than having to join the Psi Corps, they were able to do almost anything they wanted. This included joining the Earth Alliance military and working for private organizations.
The P Scale or Psi Scale is a method of measuring telepathic power used by the Psi Corps with lower ratings are more common than higher ones. However, the stronger the telepath's P-level, the more control and discipline is needed as it becomes much harder to block out the random thoughts and voices of others, a low-eb background 'noise' is generally heard by all teeps above a P-5 in their own thoughts. Training and a lot of focus is required to control and quiet down the background noises mentally heard by telepaths.
Mention is made in the show and related media of individuals who may be so powerful as to rate outside the scale entirely, often referred to as "P13"s.
The scale does not measure telekinetic abilities, but as one out of 10,000 human telepaths have TK and roughly one out of three telekinetics (teeks) is sane, this is not a significant issue.
The telepathic measurement systems of alien races are not described in the series, nor are nonhuman telekinetics mentioned.
A telepath is usually depicted as being born with telepathic abilities or developing them gradually in childhood. But in the case of those people with latent telepathic abilities, the ability can be suddenly switched on. Stress or body changes can cause this.
People experiencing a mind burst are usually taken in for medical care. When they wake up, a trained telepath is usually on hand to help them. Prior to the Telepath War, new telepaths were either made to join the Psi Corps or take drugs to block their abilities. Many telepaths ran away to keep from being forced into the Corps. After the war, telepaths had more freedom in choosing their futures.
People experiencing a mind quake are always taken in for medical care. When they wake up, a trained telepath is usually on hand to help them and if they prove too unstable they are given drugs to block their abilities, or they are neutralized by involuntary surgery.
The effects of Dust seem to be a combination of LSD and cocaine, with the user experiencing some types of Psi powers for the duration of the "high." It is targeted at humans, but one episode follows G'Kar, a non-human Narn, who has tried it to get a taste of the Psi powers his race has lost.
Dust is revealed to be a covert program of the Psi Corps. Officially it began as way to locate latent telepaths, and perhaps to amplify the powers of known telephaths. No mention is made of the cash flow inherent in such a popular form of high value contraband that would flow to Psi Corps.
The Psi Corps Trilogy: