Some text I’ve just added to WikiPedia (apart from the first paragraph, ref. 2 and the paragraph that cites it):
Antagonists to the Church of Scientology are declared by the church to be “antisocial personalities“, Potential Trouble Sources (PTS), or Suppressive Persons (SPs). The Church of Scientology teaches that association with such persons impedes one’s progress along the Bridge to Total Freedom.
In a Hubbard Communication Office Bulletin (the official policy of the Church of Scientology), L. Ron Hubbard sets out the doctrine that by being connected to Suppressive Persons, a Scientologist could become a Potential Trouble Source (PTS):
A Scientologist can become PTS by reason of being connected to someone that is antagonistic to Scientology or its tenets. In order to resolve the PTS condition, he either HANDLES the other person’s antagonism (as covered in the materials on PTS handling) or, as a last resort when all attempts to handle have failed, he disconnects from the person. He is simply exercising his right to communicate or not to communicate with a particular person.
The bulletin goes on to set out the urgency of disconnecting oneself from an SP:
To fail or refuse to disconnect from a suppressive person not only denies the PTS case gain, it is also supportive of the suppressive—in itself a Suppressive Act. And it must be so labeled.
According to Church statements, disconnection is used as a “last resort”, only to be employed if the persons antagonistic to Scientology do not cease their antagonism — even after being provided with “true data” about Scientology, since it is taught that usually only people with false data are antagonistic to the Church. 
A belief that disconnection was not being used as a last resort led a number of Scientologists to resign from the Church of Scientology in 1984, while keeping their allegiance to the beliefs of Scientology. A local paper of the Church’s East Grinstead base quotes a joint statement from a group of these former members:
“Because we are fully aware that Mr Hubbard’s writings encourage the unity of the family we cannot tolerate a misrepresentation or misapplication of them that encourages otherwise.”
Disconnection in Practice
The official New Zealand government report into the Church of Scientology (the Dumbleton-Fowles report) quoted from a number of disconnection letters. This is from teenage Scientologist Erin O’Donnell to her non-Scientologist aunt:
“I am disconnecting from you from now on. If you try to ring me I will not answer, I will not read any mail you send, and I refuse to have anything to do with you in any way whatsoever. All communication is cut completely.”
In 1966 UK newspaper the Daily Mail quoted a disconnection letter from Scientologist Karen Henslow to her mother
I am hereby disconnecting from you because you are suppressive to me. You evaluate for me, invalidate me, interrupt me and remove all my gains. And you are destroying me.
“I [unreadable] from this time consider myself disconnected from you and I do not want to see you or hear from you again. From now you don’t exist in my life.
“That’s it. Karen.”
Another investigation by the Daily Mail, in 1984, brought up other claims of disconnection.
“A boy of 13 has told his father he will never see him again. A woman claims her fiancé was forced to give up plans for marriage and leave her.”
The fiancé concerned claimed that “it was a personal decision” and a Church of Scientology spokesman was quoted as saying “If somebody you are associated with directly makes your life a misery, it may be necessary to drop your contacts with them. It is certainly not our policy to split up relationships.”
Also in 1984, the Mail on Sunday (a UK national paper) quoted Gulliver Smithers, a former Scientologist who had left the group’s base at Saint Hill Manor, East Grinstead at age 14.
“Disconnection is part of everyday life at Saint Hill. It goes round by word of mouth when someone is an outcast. He or she is just ignored and shunned. It was what we were brought up to do.”
In 1995, the UK local paper Kent Today quoted Pauline Day, who claimed to have received a disconnection letter from her Scientologist daughter Helen, who had then changed her phone number and dropped all contact. A spokeswoman for the Church of Scientology responded, “This was a decision made independently by Helen and has nothing to do with the church at all.”
Other disconnection letters have been posted online
(More about Scientology on my Scientology critics’ site)
- L. Ron Hubbard. “PTSness and DISCONNECTION”, Hubbard Communication Office, 1983-09-10.
- Church of Scientology What is Disconnection? (archive.org copy of website accessed 4/19/06)
- “Buy-out bid for sect HQ: Factions announce plans to fight ‘disconnections'”, East Grinstead Courier, 1984-02-16.
- “Sect row over policy: Members Quit in ‘Disconnection’ Protest”, East Grinstead Courier, 1984–02-09.
- Sir Guy Richardson Powles, E. V. Dumbleton. “The Commission of Inquiry Into the Hubbard Scientology Organisation in New Zealand”, 1969-06-30.
- “Minister is asked to investigate… The case of the processed woman”, Daily Mail, 1966-08-22.
- Peter Seymour. “‘We disconnect you'”, Daily Mail, 1984-02-11.
- “Hubbard Youth: The teenage bullies who reign supreme over a sinister cult”, Mail on Sunday, 1984-07-29.
- Clare Jardine. “Talk To Me, Plea By Cult Girl’s Mum”, Kent Today, 1995-05-20.
- “Our Little Boy Lost: Grandparents in Legal Battle for the right to see two-year-old Sam”, Daily Mail, 1995-05-29.
- Gormez, Michael (2005-04-23). Dear Dad… Scientology disconnect policy at work. Retrieved on 2008-02-26.