So far, five American states have legalized gay marriage: four New England states - Connecticut, Maine, Massachusetts and Vermont - plus (more surprisingly) Iowa, heart of heartland America.

Why isn't Maryland, one of the nation's more progressive states, a member of this small but growing club?

The proximate reason is that the state judiciary has yet to rule in favor of gay marriage. In September 2007, the Maryland Court of Appeals, reversing an earlier decision by the Baltimore Circuit Court, ruled 4-3 to uphold the state's statutory ban on gay marriage.

The ultimate obstacle, however, is the state legislature, where the Democrats enjoy comfortable majorities in both chambers but conservative Democrats remain resistant. Demographically, they tend to be white legislators from the Eastern Shore, Western Maryland, parts of Southern Maryland and the Baltimore County suburbs, along with a significant contingent of African-American Democrats.