The church has been less than forthright with the implications of publicly recognizing same sex marriage, using "...no congregation or minister can be forced to officiate at a same-sex marriage unwillingly" more as an opiate to secure acquiescence without substantive defense for voices of dissent.

Legally the issue is not "discrimination" as any refusal is discrimination, but "whether discrimination by refusal of same sex marriage solely because of gender [sexual orientation] within a religious body which publicly declares recognition of same sex marriage is arbitrary".

The recent Supreme Court of Canada decision Syndicat Northcrest v. Amselem [2004] 2 S.C.R. 551
http://www.lexum.umontreal.ca/csc-scc/en/pub/2004/vol2/html/2004scr2_0551.html
definition of religious belief as specific to the individual not the religious body, "freedom of religion...does not require a person to prove that his or her religious practices are supported by any mandatory doctrine of faith", offers individuals defense for refusal which is not arbitrary within a religious body which publicly recognizes same sex marriage.

Also of interest is the statement "it is not within the expertise and purview of secular courts to adjudicate questions of religious doctrine".

The situation for congregations varies with the specific human rights legislation of different jurisdictions
http://www.cdp-hrc.uottawa.ca/links/sitescan_e.html

Canadian Charter of Rights and Freedoms
Canadian Human Rights Act
Alberta Human Rights, Citizenship and Multiculturalism Act
BC Human Rights Code
Manitoba Human Rights Code
New Brunswick Human Rights Act
Newfoundland Human Rights Code
Northwest Territories Human Rights Act
Nova Scotia Human Rights Act
Nunavut Human Rights Act
Ontario Human Rights Code
Prince Edward Island Human Rights Act
Québec Charter of Human Rights and Freedoms
Saskatchewan Human Rights Code
Yukon Human Rights Code

Quebec [the only jurisdiction which provides "...no priest or other minister of religion may, even in judicial proceedings, disclose confidential information revealed to him by reason of his position or profession, unless he is authorized to do so by the person who confided such information to him or by an express provision of law"] verbally permits refusal of same sex marriage only where the religious body permits congregations to refuse
http://www.cdpdj.qc.ca/en/commun/docs/charter.pdf

10. Every person has a right to full and equal recognition and exercise of his human rights and freedoms, without distinction, exclusion or preference based on race, color, sex, pregnancy, sexual orientation, civil status, age except as provided by law, religion, political convictions, language, ethnic or national origin, social condition, a handicap or the use of any means to palliate a handicap.

Ontario permits only the person registered under section 20 of the Marriage Act to refuse
http://192.75.156.68/DBLaws/Statutes/English/90h19_e.htm

Solemnization of marriage by religious officials
18.1 (1) The rights under Part I to equal treatment with respect to services and facilities are not infringed where a person registered under section 20 of the Marriage Act refuses to solemnize a marriage, to allow a sacred place to be used for solemnizing a marriage or for an event related to the solemnization of a marriage, or to otherwise assist in the solemnization of a marriage, if to solemnize the marriage, allow the sacred place to be used or otherwise assist would be contrary to,
(a) the person’s religious beliefs; or
(b) the doctrines, rites, usages or customs of the religious body to which the person belongs

the "doctrines, rites, usages or customs" referenced are those of the religious body, not of the congregation which has no separate status; and the province verbally interprets

refusal to permit use of a sacred place by a recognized person registered under section 20 of the Marriage Act with inconsistent religious beliefs to those within the congregation, within a religious body that publicly recognizes both same sex marriage and the right of congregations to refuse, is possible discrimination; and
refusal to issue call to ministry personnel based on sexual practice is employment discrimination only where policy of the religious body forbids such discrimination.

Alberta interprets marriage as "with a person of the opposite sex".

Other jurisdictions have no provisions for refusal of same sex marriage other than "bona fide qualification" or "reasonable cause".

The Canadian Charter of Rights and Freedoms
http://laws.justice.gc.ca/en/charter/index.html
protects individuals not private bodies such as congregations, making wording of the refusal critical

draft wording being considered
uses "Elders" not "Session" as the term references the individual not a private body
"representative of" is expressed in bylaw 135
the wording of the basis is "Pastoral Charge" though the bylaws recognize "There shall be a Session for the Pastoral Charge. Where the Pastoral Charge consists of more than one (1) Congregation, there may be a Session for each Congregation, in which case these Sessions shall jointly constitute the Session for the Pastoral Charge." [bylaw 140]
"individually and severally" to meet both Charter and United Church of Canada requirements
"inconsistent with our religious belief" per Charter article 2. (a) "freedom of conscience and religion"
"and not the subject for..." expresses what within the context of section 18.1 of the Ontario Human Rights Code without being derogatory

We, the Elders representative of _______________ Church, _______________, Ontario, in exercise of our responsibility for
"oversight of the spiritual interests of the Pastoral Charge" [basis 5.8.4]; and
"the order of public worship, including the service of praise and the use of the church edifice" [basis 5.10.1(5)];
do individually and severally find same sex marriage inconsistent with our religious belief and not the subject for authorization of marriage by a person registered under section 20 of the Marriage Act or use of the church edifice for an event related to a same sex marriage within this congregation.