““Custody” is not defined in Ontario legislation, though its meaning in family law is generally understood. It consists of a bundle of rights and obligations, called “incidents” in sections 20 and 21 of the Children’s Law Reform Act, R.S.O. 1990, c. C.12, as amended. Family law cases often deal with the allocation of rights of custody. Those rights include the right to physical care and control of the child, to control the child’s place of residence, to discipline the child, to make decisions about the child’s education, to raise the child in a particular religion or no religion, to make decisions about medical care and treatment. The incidents of custody can be dealt with all together or separately, according to section 21, and today it is common for parents who have separated to agree, and for courts to order, that some incidents of custody are jointly vested in the parents and some belong to one parent exclusively. If a custodial right is joint, it may be exercised by any one of the persons who has it…
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Historically the Crown, exercising the authority of parens patriae through the Court of Chancery in England and Upper Canada and later the consolidated superior court of Ontario, had the sole authority to transfer custodial rights in respect of a child. Gradually over the last 200 years, statutes were passed dealing with court orders for custody, guardianship and wardship of children, but it was only in 1978 that legislative recognition of private contractual arrangements for custody first occurred in Ontario, in the Family Law Reform Act, 1978, S.O. 1978, c. 2.
The agreement entered into in this case is ineffective under the law to confer joint custodial rights over Valerie on the applicant. The only instruments (other than court orders) recognized by Ontario law as conferring custodial rights over a child are marriage contracts, cohabitation agreements and separation agreements (see section 20 (7) above and Family Law Act, R.S.O. 1990, c. F.3, as amended, sections 52–54), wills (see Children’s Law Reform Act, R.S.O. 1990, c. C.12, as amended, section 61) and temporary care and special needs agreements with a children’s aid society (see Child and Family Services Act, R.S.O. 1990, c. C.11, as amended, Part II).”
Chou v. Region District School Board, 2005 CanLII 11195 (ON SC) at 21-23