As courts grapple with same-sex marriage laws, a new twist emerges: How do you define man and woman?

After suffering from a seemingly minor foot injury, a series of operations and blood clots tragically ended Jonathan Littleton?s life in 1996. Aggrieved, Littleton?s widow, Christie Lee, blamed the doctors and filed a medical malpractice lawsuit.But a Texas court threw out the lawsuit. Because Christie Lee Littleton was born a man ? she had a sex-change operation when she was 27 ? the court ruled that the marriage was invalid and that she had no legal ground to sue as a spouse.

Twenty years earlier a court in New Jersey settled a similar case the opposite way: The wife had been born a man but underwent hormone therapy and various surgeries to live as a woman. After she and her husband split up, she sued for spousal support. The husband argued that because his wife was born a man, the marriage wasn?t legal and he owed her nothing. The court ruled that for the purpose of marriage, she was a woman and the husband was forced to pay spousal support.

How courts define gender is garnering attention in legal circles while states consider new laws banning same-sex marriage. In November, Virginia voters will vote on a constitutional amendment defining marriage as ?a union between one man and one woman.? But how does the law determine who is a man and who is a woman?

For years, judges across the country have wrestled with the question of how to define gender. Rulings have been inconsistent across the states, but most courts tend to rule in line with the Texas court: Gender is fixed at birth, and sex-change operations, or sex-reassignment surgeries, do not change a person?s legal gender.

So if Texas says someone?s sex cannot change, does that mean Christie Lee Littleton can only marry women? That scenario would look a lot like same-sex marriage.