A group of 100 conservative lawyers and academics recently filed a Supreme Court brief arguing that gay marriage will cause 900,000 abortions over the next 30 years. Leading the charge is lawyer and former Antonin Scalia law clerk Gene Schaerr, who summarized the argument in a recent piece for the Heritage Foundation.

It goes something like this: same-sex marriage "undermines" traditional marriage, which leads to lower marriage rates. And lower marriage rates mean more abortions, because unmarried women get more abortions than married women do. This represents "a short and simple causal chain that the Supreme Court would be wise not to set in motion," according to Schaerr.