When Andrea Louise Campbell's sister-in-law, Marcella Wagner, was run off the freeway by a hit-and-run driver, she was seven-and-a-half months pregnant. She survived-and, miraculously, the baby was born healthy. But that's where the good news ends. Marcella was left paralyzed from the chest down. This accident was much more than just a physical and emotional tragedy. Like so many Americans-50 million, or one-sixth of the country's population-neither...