When Vioxx was withdrawn from the market in 2004, it was significant because the painkiller had been prescribed to millions of people, not to mention it had netted billions for Merck.

But news of increased risk of heart attack and stroke pushed the drug into the center of a still-lingering debate that questions what role the FDA should have played in Vioxx's tenure in the market.

For years, the FDA has been criticized about the way ...