Massachusetts is reeling from a massive scandal in its state crime lab. Details are still emerging about what officials call a "rogue chemist" who may have mishandled evidence in as many as 40,000 cases over 10 years. It could mean the unraveling of countless convictions. Even lawyers prone to hyperbole may not be overstating it when they call the scandal a catastrophic failure and unmitigated disaster. "Any person who's been convicted of a drug crime in the last several years whose drugs were tested at the lab was very potentially a victim of a very substantial miscarriage of justice," says...