Measles was declared eradicated in the United States 15 years ago, but a recent outbreak that began in Disneyland has sparked controversy over "personal-belief exemptions." As the outbreak was spreading in Southern California, it was reported that some stricken neighborhoods had low vaccination rates. That was traced to the state's liberal allowance of "personal belief exemptions." Now an effort to ban them has led to heated controversy — not just in Sacramento but other state capitals as well. Marci Hamilton is author of God vs. the Gavel: The Perils of Extreme Religious Liberty. A professor at Benjamin Cardozo School of Law in New York, she says it's about weighing individual rights and public health.