Disconnection is the severance of all ties between a Scientologist and a friend, colleague, or family member deemed to be antagonistic towards Scientology. The practice of disconnection is a form of shunning. Among Scientologists, disconnection is viewed as an important method of removing obstacles to one's spiritual growth. In some circumstances, disconnection has ended marriages and separated children from their parents.

The Church of Scientology has repeatedly denied that such a policy exists, though as of February 2012^[update] its website acknowledged the practice and described it as a human right. In the United States, the Church has tried to argue in court that disconnection is a constitutionally protected religious practice. However, this argument was rejected because the pressure put on individual Scientologists to disconnect means it is not voluntary.

Antagonists to the Church of Scientology are declared by the Church to be suppressive persons (SPs) or potential trouble sources (PTSes). The Church teaches that association with these people impedes a member's progress along the Bridge to Total Freedom.^{[citation needed]}

In Introduction to Scientology Ethics, 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.

Hubbard defined "handling" as an action to lessen a situation towards an antagonistic individual by means of communication, and disconnection as a decision to cut communication with another individual. Hubbard also wrote that ethics officers should recommend handling rather than disconnection when the antagonistic individual is a close relative. He also stated that failure, or refusal, to disconnect from a suppressive person is a suppressive act by itself. In one case cited by the UK government, a six-year-old girl was declared suppressive for failing to disconnect from her mother. Sociologist Roy Wallis reports that Scientologists connected to a suppressive would usually be required to handle or disconnect, although he found some "Ethics Orders" which ordered unconditional disconnection.

According to Church statements, disconnection is used as a "last resort", only to be employed if the people 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.

Originally, disconnection involved not only ending communication with someone but also declaring it publicly. The Scientology publication The Auditor included notices of disconnection from named individuals. It was also common for Scientologists to send short letters to the suppressive person, to warn them that they were disconnected. Roy Wallis interviewed a number of people who had been declared suppressive, some of whom had received hundreds of these letters. The Scientologist was also required to take "any required civil action such as disavowal, separation or divorce" to cut off contact with the suppressive.