A Federal judge in Massachusettes has struck down the Defence of Marriage Act (DOMA). The decision is likely to be appealed to the Supreme Court.

The Act defines marriage as the union of a man and a woman for the purposes of federal law, and was passed in 1996, by overwhelming votes in both the House of Representatives and the Senate. It prevents a same-sex marriage in one state from being recognised by court in another state, thereby forcing a change to that state’s law.

Last week, Judge Joseph L. Tauro decided in favor of the a U.S. Postal Service employee whose same-sex ‘marriage’ was denied employer-sponsored health insurance.

Judge Tauro ruled that there is no “rational basis” to support DOMA and that DOMA could only have been motivated by “irrational prejudice” and “animus.”

He rejected the arguments on behalf of the US Government, who argued that protecting marriage as the union of husband and wife would advance the public interest in “responsible procreation and childbearing.”

Previous U.S. Supreme Court rulings stated that marriage is “fundamental to our very existence and survival” and has “more to do with the morals and civilization of a people than any other institution.”

However, Judge Tauro ruled that the public interest in procreation and childrearing does not provide a rational basis for upholding DOMA. The judge also declared that, under the U.S. Constitution, “defending traditional notions of morality” is not a permissible basis for supporting DOMA.

In a related opinion, the judge also ruled that, by enacting and enforcing DOMA, the federal government “plainly encroaches upon the firmly entrenched province of the state, and, in doing so, offends the Tenth Amendment [to the U.S. Constitution].”

“DOMA fails to pass constitutional muster,” he wrote about a key section of the law, because it “violates core principles of equal protection.”

The judge also rejected the argument that DOMA encouraged heterosexual couples to procreate and rear their own children more responsibly.

Such an aim, he said “would not provide a rational basis for denying federal recognition to same-sex marriages”.

He added: “Such denial does nothing to promote stability in heterosexual parenting.”

Judge Tauro also said that he could not “discern a means by which the federal government’s denial of benefits to same-sex spouses might encourage homosexual people to marry members of the opposite sex”.

Pro family groups have expressed their dismay at the ruling.

Southern Baptist Seminary president and commentator Albert Mohler Jr said that the ruling, even though it applied only to Massachusetts would have effects that “extend far beyond the Bay State”.

Archbishop Joseph Kurtz of Louisville, chairman of the United States Conference of Catholic Bishops (USCCB) Ad Hoc Committee for the Defense of Marriage, said in a release on Monday that Tauro’s ruling “is a great disservice not only to truth but to the good of our nation.”

The Archishop said: “The state has a duty to employ the civil law to reinforce — and, indeed, to privilege uniquely — this vital institution of civil society. The reasons to support marriage by law are countless, not least to protect the unique place of husbands and wives, the indispensable role of fathers and mothers, and the rights of children, who are often the most vulnerable among us.”