“The Ontario Court of Appeal in Mattina v. Mattina, 2018 ONCA 867 set out that modern costs rules are designed to foster four fundamental purposes:
a) to partially indemnify successful litigants;
b) to encourage settlement;
c) to discourage and sanction inappropriate behaviour by litigants and;
d) to ensure that cases are dealt with justly under subrule 2 (2) of the Family Law Rules (all references to the rules in this decision are to the Family Law Rules).
Costs can be used to sanction behaviour that increases the duration and expense of litigation or is otherwise unreasonable or vexatious. In short, it has become a routine matter for courts to employ the power to order costs as a tool in the furtherance of the efficient and orderly administration of justice. See: British Columbia (Minister of Forests) v. Okanagan Indian Band, 2003 SCC 71 (CanLII), 2003 S.C.C. 71, paragraph 25.
Costs awards are discretionary. Two important principles in exercising discretion are reasonableness and proportionality. See: Beaver v. Hill, 2018 ONCA 840.
An award of costs is subject to the factors listed in subrule 24 (12), subrule 24 (4) pertaining to unreasonable conduct of a successful party, subrule 24 (8) pertaining to bad faith, subrule 18 (14) pertaining to offers to settle, and the reasonableness of the costs sought by the successful party. See: Berta v. Berta, 2015 ONCA 918, at paragraph 94.”