For many years, one of Bill and Hillary Clinton's closest friends, TV producer Linda Bloodworth-Thomason, has been fond of saying that when the Clintons "are dead and gone, each of them is going to be buried next to a president of the United States."

It is an idea that the Clintons began talking about decades ago. Back in 1974, Bill Clinton told his friend Diane Kincaid that Hillary "could be president someday." During his own presidential campaign in 1992, he said in an interview, "Eight years of Hillary Clinton? Why not?"

We now face the extraordinary possibility of having two presidents in the White House who are married to each other. That prospect is something that never occurred to our nation's founders, and is only now beginning to catch the attention of the public, with Hillary Clinton's position as front-runner for the Democratic presidential nomination.

Imagine being asked to serve as her running mate, knowing that her husband would be far more influential than any vice president. What would a potential secretary of state face now that Sen. Clinton has already said she would use her husband as ambassador to the world? As a former president, would Mr. Clinton read the daily intelligence briefing? His unofficial portfolio would potentially overlap with everyone in authority, without his being subject to Senate confirmation.

The federal anti-nepotism law enacted in December 1967 -- partly as a reaction to John F. Kennedy's appointment of his brother Robert as attorney general -- prohibits any official in the three branches of government, including the president, from appointing a relative to a job over which that official has authority or control. This means Mr. Clinton could not be a cabinet secretary or an ambassador, or White House chief of staff. His role would be necessarily ambiguous. At a time when voters are crying out for more openness in government, such an arrangement raises questions about transparency and accountability.