In the two years since he was tested, Smith has become a one-man army trying to advance a relatively new legal term - "paternity fraud." He has recruited Georgia legislators to draft a proposed law (HB 369), joining four other states (Arkansas, Ohio, Louisiana, Colorado) to provide "accused fathers" with the legal mechanism to seek DNA testing and, in cases of exoneration, to be relieved of financial responsibilities for a child not their own.

"Why hold someone responsible for what someone else did?" asks Smith. "Common sense, decency and logic say he's not financially responsible for something he didn't do."

Smith's personal nightmare began in 1999, 10 years after he'd taken responsibility for the child he thought was his. Until then, he says he voluntarily paid his child support and helped raise the girl. Then in 1999, the mother went to court to try to increase her child support payments to $1,300 per month, or 42 percent of Smith's take-home pay. An engineer with a telecommunications company, Smith earned a good salary, but he also had a wife and two children of his own.

In the midst of court proceedings one day - in a scene made for Hollywood - Smith was going to pick up his daughter when a billboard caught his eye. "Who's the Father?" it said and listed a toll-free number for a DNA-testing company. Acting on instinct, Smith made the call.

He's been tested twice now, and both times with the same result: There is zero chance he's the girl's father. A judge has ruled that he no longer has to pay child support. And one 12-year-old girl no longer has a father.

That's the sad part of the story, and the piece that usually dampens sympathy for men such as Smith. How can you suddenly stop loving a child for whom you've always been Dad? How can you abandon a child who needs you? These are tough questions and prompt emotions that interfere with one's usual impulse to fairness.

But fair is fair, and the truth looks like this: The mother who lies about paternity is guilty of fraud and deserves condemnation at least equal to what we assign fathers who abandon their children. In no other imaginable scenario, meanwhile, do we punish victims of a false allegations. As Smith points out on his Web site (www.paternityfraud.com), fraud is a crime that under any other circumstances would be punishable in criminal and civil courts.

In fact, Smith has filed a civil suit against his ex-lover, hoping to recoup the $80,000 he's paid her. And though he'd like to see his former daughter, he's steering clear of the child custody system that he says indentured him to pay for another's sins.

Smith's activism wouldn't be possible, of course, without recent technological advances in DNA testing, the advent of which has been a mixed blessing. Knowledge is sometimes ruthless and can exact painful consequences. Men often are devastated by the results and, of course, any child so ill-conceived loses more than money and pride.

One can't blame Smith and others who've fallen prey to paternity fraud. But the whole business does make one nostalgic for those stodgy old days when marriage preceded procreation, and Mom and Dad knew exactly who they were.