v. — Law, Administration
to detain a prisoner who otherwise would be released on serving two-thirds of a sentence.
Type: 3. Semantic Change — Inmates who have served two-thirds of a prison sentence are required by law to serve out their sentence in the community under what was called "mandatory supervision" until 1992. If an offender was deemed a danger, he or she could be gated (see the 2014 quotation). In 1983, gating was deemed illegal by the Supreme Court which deemed that a return to prison could only take place if the released person broke the conditions of release or re-offended. However, under new laws, although the Parole Board does not control mandatory release, it may issue a detention order if the prisoner is deemed likely to commit a serious offence.
The term is perhaps inspired by an older meaning of gate 'to confine (an undergraduate) to the precincts of the college, either entirely or after a certain hour.' (OED-3, s.v. gate v.1).
See also COD-2, s.v. "gate (1) trans.verb (3)", which is marked "Cdn".