There seems to be much confusion in the current debate over marriage. Hopefully it's not being done on purpose to cloud the issue. Let's make one thing very clear: those of us who support marriage as it has been since the dawn of time respect the liberty of others to live their lives as they choose. But governmental redefinition of marriage is a power grab that attacks civil society.

That's right. We cannot hope to limit government if we do not stand up for marriage. Marriage is the foundation of America's cultural stability and economic prosperity. As the Supreme Court considers two cases challenging marriage as the union of a man and a woman, it should resist a ruling that would usurp authority from citizens and their elected officials, which would be the biggest power grab of them all.

Without strong families grounded in marriage, we cannot hold back the ever-expanding power of government. As the marriage culture weakens, Big Government grows. Just look how the welfare state has expanded as the unwed childbearing rate has grown from single digits in the 1960s to more than 40% today.

Marriage policy exists to encourage a man and a woman to commit to each other permanently and exclusively as husband and wife and to be father and mother to any children. Sound marriage policy strengthens civil society and reduces the role of government.

The erosion of marriage costs taxpayers. And it's not just conservatives who say this. Even the left-leaning think tank, Brookings Institution, attributed $229 billion in welfare expenditures between 1970 and 1996 to the breakdown of marriage.

Marriage is our best anti-poverty program. As the Heritage Foundation's welfare expert Robert Rector has pointed out, marriage reduces the probability a child will be poor by 80%, dramatically diminishing the odds of ending up on welfare.

Even President Obama agrees that the facts about family breakdown are well-established. As he said in his 2008 fatherhood speech: "We know the statistics -- that children who grow up without a father are five times more likely to live in poverty and commit crime; nine times more likely to drop out of schools and twenty times more likely to end up in prison. They are more likely to have behavioral problems, or run away from home, or become teenage parents themselves. And the foundations of our community are weaker because of it."

Fathers matter, and marriage helps to connect fathers to mothers and children.

But how can the law teach that fathers are essential if policy redesigns marriage to make fathers optional? Redefining marriage would reject the ideal that a child needs a mom and a dad.

Decades of research show that children generally do best when raised by a married mother and father. If marriage policy teaches a lie about what marriage is, and delinks childbearing and rearing from marriage, it would result in liberals advocating for more state intervention to pick up the pieces of a broken marriage culture and cause welfare programs to grow even more.

Redefining marriage does not simply enlarge its scope to include more people, as some suggest. No, it rejects the twin realities at the heart of the institution: marriage is based on the biological fact that reproduction depends on a man and a woman and children need a mother and a father. It replaces it with an entirely new principle: that marriage is whatever emotional bond the government says it is.

We can treat citizens fairly and fix policy problems without redefining marriage. The lawsuit before the Supreme Court on the Defense of Marriage Act, for example, involves a woman in a lesbian relationship who was forced to pay more than $350,000 in federal estate taxes when her partner passed away because she didn't qualify for a marital exemption. This is why we have argued for eliminating the estate tax for more than 15 years.

The death tax is bad tax policy, period -- for all Americans. We can remove this burden without rushing to abolish marriage as the union of a man and a woman. Everyone is free to love whom they want but no one is entitled to redefine a foundational institution of civil society that has existed for centuries.

Whatever anyone thinks about marriage as a policy matter, unelected judges shouldn't try to settle this question for the entire country. The Supreme Court should uphold marriage and restore to the American people the authority to determine marriage policy. It's time to restore constitutional government and that means standing up for our most fundamental, pre-political institution: marriage, the union of one man and one woman.

-Jim DeMint, the former Republican senator from South Carolina, is the president-elect of The Heritage Foundation.