Some legislatures have voluntarily established domestic partnership relations by statute instead of being ordered to do so by a court. Although some jurisdictions have instituted domestic partnerships as a way to recognize same-sex unions, domestic partnerships may involve either different-sex or same-sex couples.

In some legal jurisdictions, domestic partners (or 'domparts') who live together for an extended period of time but are not legally entitled to common-law marriage may be entitled to legal protection in the form of a domestic partnership. Some domestic partners may enter into domestic partnership agreements in order to agree contractually to issues involving property ownership, support obligations, and similar issues common to marriage. (See effects of marriage and palimony.)

One of the purposes of domestic partnership relation is to recognize the contribution of one partner to the property of the other. In the common law, devices such as the constructive trust are available to protect spouses in legal or common-law marriages. In civil law jurisdictions, such trusts are generally not available, prompting courts to find alternative ways to protect the partner who contributes to the other's property.

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