s of matrimony, with all the rights and obligations that mightarise.(9)This country's division of constitutional responsibility between the federal and provincial governments creates a peculiarlyCanadian set of legal problems with both registered domestic partnerships and "same sex marriage." Both levels ofgovernment have some responsibility within their respective areas of jurisdiction in responding to the claims posed by M v H.for legal recognition of same sex relationships.The federal government has responsibility for "marriage and divorce" under s.91(26) of the Constitution Act, 1867. Thisgives the federal government the responsibility for enacting laws governing capacity to marry, while the provinces havejurisdiction over "solemnization of marriage" under s. 92 (12) of the Constitution Act, and "property and civil rights" unders. 92(13). It is clear that in 1867 the definition of marriage was "the voluntary union of one man and one woman to the exclusion of allothers,"(10) and that the ability to consummate the marriage by having heterosexual intercourse was an essential element of"marriage."(11) While the federal government has modified some of the common law rules governing the capacity of a manand a woman to marry, for example to allow an uncle to marry his neice,(12) it has not tried to change the basic common lawdefinition of marriage.(13) There is an argument that it would be ultra vires s. 91(26) for the federal government to enactlegislation that would fundamentally alter and expand the very nature of "marriage" by allowing same sex couples to "marry."An argument could be made that the federal government could not expand its jurisdiction by fundamentally altering the legalconcept of "marriage" from what it was in 1867. Ultimately I do not find this argument I persuasive, but it is an argument thatwill need to be considered in any law reform undertaking.I believe that under s. 91 (26) of the Constitution Act the federal gove...