Section 24 of the Children’s Law Reform Act compels the merits of a custody or access application to be grounded on the best interests of the child(ren). To determine the best interests of a child, courts consider all the needs and circumstances of the child, including:
a) the love, affection and emotional ties between the child and,
(i) each person entitled to or claiming custody of or access to the child,
(ii) other members of the child’s family who reside with the child, and
(iii) persons involved in the child’s care and upbringing;
b) the child’s views and preferences, if they can reasonably be ascertained;
c) the length of time the child has lived in a stable home environment;
d) the ability and willingness of each person applying for custody of the child to provide the child with guidance and education, the necessaries of life and any special needs of the child;
e) the plan proposed by each person applying for custody of or access to the child for the child’s care and upbringing;
f) the permanence and stability of the family unit with which it is proposed that the child will live;
g) the ability of each person applying for custody of or access to the child to act as a parent; and
h) the relationship by blood or through an adoption order between the child and each person who is a party to the application.
Generally, the courts are not inclined to involve children in custody and access hearings. However, custody assessments may be ordered in cases where more light needs to be shed on the issues. Custody assessments are generally conducted by psychologists or social workers who bring voice to the children’s best interests. The assessors typically speak with the parties involved, children, grandparents, teachers, doctors, and other important people, to determine the best interests of children. Some teenage children may voice their concerns to the court themselves, if the court, children and parties see their involvement in court hearings necessary.
http://www.canlii.org/en/on/laws/stat/rso-1990-c-c12/latest/rso-1990-c-c12.html