Paul Roberts, left, and Pum van Veldhoven have lived common-law for about 10 years. After Thursday's Supreme Court ruling, he could walk away with their Ottawa townhouse if they ever split up. Photo: Dave Chan/The Globe and Mail

If you chose not to walk up the aisle, don't expect to get half the house.

In a ruling that could come as a surprise to many co-habiting partners, the Supreme Court of Canada said Thursday that property rights are a benefit — or perhaps a price — of getting married.

"The decision to marry or not is intensely personal and engages a complex interplay of social, political, religious and financial considerations by the individual," an 8-1 majority said.

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• Social trends reporter Erin Anderssen asks experts
  about the ruling. Their advice to couples? Get a contract


• In another ruling Thursday, the Supreme Court
  rejected a landmark attempt to have social benefits
  secured as a constitutional guarantee. Please read
  Kirk Makin's report and the Globe's editorial view

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"People who marry can be said to freely accept mutual rights and obligations," the court reasoned. "A decision not to marry should be respected because it also stems from a conscious choice of the parties. If they have chosen not to marry, is it the state's task to impose a marriage-like regime on them retroactively?"

The ruling means that common-law partners cannot claim an equal division of matrimonial property if their relationship breaks down. It also means that hundreds of property claims filed by common-law spouses are headed for the trash can, family-law expert Philip Epstein said.

"They are wiped out," Mr. Epstein said in an interview. "If people want property rights, they should get married."

The law was thrown into doubt a couple of years ago by appellate-court rulings in Nova Scotia and Saskatchewan. By overturning the Nova Scotia ruling Thursday, the Supreme Court restored a measure of certainty to matrimonial division schemes in each province.

Mr. Epstein pointed out that as disappointing as the judgment is for heterosexuals living in common-law relationships, it could be a godsend for same-sex couples who have been waging a sustained court battle for the right to marry.

"The court is saying that the law is not discriminatory because people have a choice whether or not to marry," Mr. Epstein said. "But it obviously follows that if they don't have that right to marry, then they do not have that choice."

The N.S. case involved Susan Walsh and Wayne Bona, a couple who co-habited for 10 years and had two children. After their breakup, Ms. Walsh wanted a share of the value of assets in Mr. Bona's name — including a modest cottage and several acres of woodland. She sought to have the province's Matrimonial Property Act declared unconstitutional on the basis that it excluded common-law partners from its definition of spouse.

"This is a really, really important case," Mr. Epstein said. "It is one of the most important family-law cases in the past decade. One of the problems in Canada is that a lot of people do not understand their rights. There are going to be some interesting conversations in homes around the country after this ruling."

The Supreme Court said the distinction between married and common-law spouses is constitutional primarily because it does not demean or impugn the dignity of those living in common-law.

Extending the legal consequences of marriage to common-law partners would "nullify the individual's freedom to choose alternative family forms, and to have that choice respected by the state," Mr. Justice Michel Bastarache said.

The sole dissenter Thursday — Madam Justice Claire L'Heureux-Dubé — said the law continues a historical pattern of treating common-law partners as if they are not a "legitimate family form."

Known throughout her career as both a family-law specialist and a frequent dissenter, Judge L'Heureux-Dubé's role in Thursday's ruling came as no surprise to many legal observers.

"This is her swan song, but I'm afraid she sings alone in this one," Mr. Epstein said.

The ruling was restricted to property rights. Courts have established in previous cases that common-law spouses do enjoy rights in the area of support.

Thursday's ruling also has no effect on "constructive-trust" provisions, which allow common-law spouses to win a share of property to which they can show they have made a direct or indirect contribution.

Mr. Epstein said the ruling is likely to make many common-law partners think seriously about making legal contracts with one another.