OLYMPIA, Wash.—Domestic partners in Washington state were granted more than 170 of the benefits and responsibilities given to married couples under a measure signed into law March 12 by Gov. Chris Gregoire.

The measure adds domestic partners to sections of laws where previously only spouses were mentioned, including areas referring to probate and trusts, community property and homestead exemptions, and guardianship and powers of attorney.

The law takes effect June 12.

The underlying domestic partnership law, passed last year, already provides hospital visitation rights, the ability to authorize autopsies and organ donations and inheritance rights when there is no will.

More than 3,500 couples have registered as domestic partners since the law took effect last year.

The measure makes dozens of changes to state law, including requiring domestic partners of public officials to submit financial disclosure forms, just as the spouses of heterosexual officials do.

It also would give domestic partners the same spousal testimony rights that married couples have, allowing domestic partners the right to refuse to testify against each other in court.

Under the measure, the process of ending a domestic partnership also would be changed, allowing the secretary of state to end partnerships only in the first five years, with several more restrictions relating to children, real property or unpaid debts.

All other partnerships would be dissolved in superior court—similar to conventional divorce.

To be registered as partners, couples must share a home, must not be married or in a domestic relationship with someone else, and be at least 18.

In a provision similar to California law, unmarried heterosexual senior couples also are eligible for domestic partnerships if one partner is at least 62.