The fact that "same-sex couples can’t marry" is an argument used by some gay and lesbian activists as well as some politicians to justify same-sex only benefits. However, more people in both of these categories now believe that it is wrong for an employer to force opposite-sex couples to marry in order to receive health and other job benefits.

There are many valid reasons why a man and a woman may choose domestic partnership over matrimony. They include philosophical, political, economic, religious, and personal considerations.

Some feminists believe that marriage historically is an institution that has oppressed women. They prefer bonding in a non-marital family unit such as domestic partnership.

Then there are women who have divorced due to domestic violence or abuse in a marriage. When they find another mate, they may be reluctant to marry, at least for a few years. They see domestic partnership as a way of establishing a family unit without surrendering themselves to a spouse through marriage.

Many seniors who are widowed and many people of all ages with serious disabilities do not marry because, if they do, they might lose pension survivor benefits or government subsidies. Other seniors are fearful that a new marriage might upset estate plans for their adult children.

There are also religious reasons. Some people whose spouses have died or who have been divorced against their will have vowed never to marry again. To them, marriage is a religious experience they will only have once in life.

Being a truly secular institution that does not require a sexual relationship as marriage presumably does, domestic partnership is another matter entirely. Widows or divorcees may want domestic partnership for purposes of companionship and security without any sexual overtones, and that should be their prerogative.

One might disagree with this premise on the theory that the law provides for ‘civil’ marriage. Fair enough, let’s look at that further.

Many people believe that marriage is essentially a religious sacrament. That is why so many religious organizations are up in arms over gay marriage.

The religious nature of marriage is not necessarily eradicated merely because the government places the word "civil" in front of it, any more than the sacrament of baptism would become a secular practice simply if the government were to pass a statute creating so-called "civil" baptism.

In the minds of many agnostics and atheists, the term "marriage" carries religious connotations which they don’t want. They prefer a truly secular institution with the secular label of "domestic partnership."

Cohabitation is now commonplace in the marital decision-making process. Most people contemplating the possibility of marriage now live in a domestic partnership as a prelude. That is a personal decision which is none of an employer’s business.

If one believes in the principle of equality, and in this case equal pay for equal work, then it should not matter whether employees are married, single, divorced, or widowed, or whether their domestic partner is a man or a woman.

Gay and lesbian groups now often include the rights of bisexuals and trans-gendered persons in their cause, and thus the acronym "GLBT" has emerged.

Should not a bisexual person have the right to register as a domestic partner if his or her primary partner is someone of the opposite-sex? Or is domestic partnership going to be turned into a ghetto institution for homosexuals only?

And what happens when a trans-gendered person who is already receiving domestic partner benefits at work for his male partner goes through sex reassignment surgery and obtains genitalia of the opposite sex? Should the couple be kicked off the benefits plan and be told they must marry before they can reapply for benefits? And does mere surgery change one’s gender for purposes of marriage or are other legal procedures required?

There is another point to consider. Opposite-sex couples may have a strong political reason for rejecting matrimony. Some men and women are standing in solidarity with gay and lesbian couples and are refusing to get legally married until gays are legally allowed to marry too. Should they be denied domestic partnership benefits in the meantime?

Some people nonetheless would resist the notion of domestic partner benefits for straight couples, arguing that if they can’t make a commitment, these couples do not deserve the benefits.

In order to get domestic partner benefits, an employee and his or her partner must sign an affidavit in which they agree to share the common necessities of life and be responsible for each other’s common welfare. This is not a free lunch.

If opposite-sex couples are willing to sign that same affidavit and assume the same responsibilities as same-sex couples are, then why should they not receive the same benefits?

Then there are conservatives who say that "living in sin" is immoral. These folks claim that giving benefits to unmarried co-habitors promotes irresponsible behavior.

Let’s stop for a moment to examine the principle underlying that argument and where it would ultimately lead.

Many people believe that a man who has divorced and remarried two times and that a unmarried women who has a baby have both engaged in sinful behavior. Under such a "morality" theory of employee benefits compensation, the man would not receive health benefits for his second or third wife and the woman would not receive benefits for her child.

Using the same "morality" standard some would impose on opposite-sex domestic partners - that no employee benefits should be given to reward irresponsible behavior - the only people who would get benefits at work would be a single person with no partner, a married couple in their first relationship, and children born in a first-time marriage.

Now for the issue of cost. Reliable studies show that such inclusive plans are not costly, with enrollment increasing by only one percent as a national average when same and opposite-sex partners are covered. That is one of the reasons why the overwhelming majority of government employers with domestic partner plans have rejected the "same-sex only" approach.

Besides these issues, there is the concern over litigation. Federal lawsuits were filed against both Bell Atlantic and the City of Chicago alleging that it is illegal sex discrimination to give benefits to some unmarried couples but not to others based on the sex of the partners. Other suits are likely to follow. California’s Labor Commissioner has ruled that government employers with "same-sex only" plans are violating the state’s civil rights laws against sexual orientation discrimination.

With all this in mind, I return to my basic premise. Compensation should be based on merit and productivity, not on factors irrelevant to job performance such as sex, sexual orientation, marital status, or personal moral viewpoint.

Thomas F. Coleman is executive director of the American Association for Single People. AASP promotes the well being and civil rights of unmarried adults, couples, parents, and families.