TRENTON - New Jersey's civil-union law has failed to provide all the benefits of marriage to at least one in five same-sex couples, a gay-rights group said yesterday.

More than 300 of the 1,514 same-sex couples who have joined in civil unions have complained to Garden State Equality, the state's leading gay-rights group, that employers have denied them benefits under the law, said David M. Smith, the group's deputy director.

"If this law is a failure, and people's rights are at stake, why must we wait to fix the problem?" asked Thomas H. Prol, a New Jersey Bar Association trustee and former cochairman of the group's Gay, Lesbian, Bisexual and Transgender Rights Committee.

More than 20 people shared their experiences with the civil-union law - all negative - during a hearing in Trenton last night to review the law's effectiveness.

Those appearing before the Civil Union Review Commission included parents of gay adults, gay-rights advocates, lawyers, and gay couples, some with children in tow. All urged the Legislature to change the law to include the word marriage.

Richard Cash and Craig Ross provided typical testimony. When Ross lost his white-collar job and tried to get benefits on his partner's plan, he said, the couple were denied despite their civil union because they aren't married.

"Calling our relationship and our legal status a civil union, I believe, gives my company an easy out," Ross said. "Calling it what it is - a marriage - makes denial of those benefits obvious for what it is: discrimination."

Garden State Equality has compiled "a mountain of new evidence showing the failure of New Jersey's civil-union law to provide equality as real marriage would," said its chairman, Steven Goldstein, who sits on the review panel.

New Jersey adopted its civil-union law in December after the state Supreme Court ruled it unconstitutional to deny same-sex couples access to marriage protections. The law went into effect in February.

As of Aug. 15, Garden State Equality said, it had received complaints from 304 couples about how employers and insurers refused to recognize civil unions. Thirty of the couples signed a letter to the governor and legislative leaders describing financial and emotional damage caused by what they perceive to be shortcomings in the civil-union law.

The civil-union legislation also created the commission that held the first of three public hearings yesterday. The panel is to report its findings annually to the governor and the Legislature.

Beth Robinson, chairwoman of Freedom to Marry in Vermont, which has had a civil-union law similar to New Jersey's for more than seven years, cautioned that the passage of time will not bring marriage equality.

"This is not a privilege. This is not a right. This is about justice," said Tom Barbera, a labor leader in Massachusetts, the only state that allows same-sex couples to marry, a right created by the state's top court.

However, not everyone wants to see gay couples allowed to marry.

Len Deo, president of the New Jersey Family Policy Council, which opposes gay marriage, said last week that the review commission wasn't aiming for an unbiased report. He said the commission had been created "to turn civil unions to full-fledged marriage."

Deo said the argument that the rights of gay couples were not fully recognized under civil unions was faulty. He pointed to United Parcel Service, which at first denied benefits to New Jersey couples with civil unions but, after reviewing the law, reversed course.

The issue of rights for gay couples has not been totally decided in New Jersey, Deo said. He said the state Supreme Court, Legislature or a popular vote would likely change the legal status.

His group is pushing for a state constitutional amendment that would ban same-sex marriage. An amendment would have to be supported by the Legislature before going to a popular vote, but the Democrats who control both houses of the Legislature oppose such a vote.

State Sen. Loretta Weinberg (D., Bergen) cosponsored New Jersey's civil-union law even though she supports calling it gay marriage. She said a "gay marriage" law would not have passed the Legislature.