Last month in the case of Phillips v. New York, a federal judge upheld a New York City policy barring unvaccinated children from schools where a vaccine-preventable illness has been diagnosed. The case received a lot of attention from the media, including the New York Times and Slate. But these articles don’t say much about what really happened in the case. Since the case dealt with the same kinds of arguments many anti-vax parents make, I went through it to acquaint myself with the law. Since I was reading up on it anyway it might be useful or interesting to other people to see how a case like that works. Bear in mind that this is a broad-strokes explanation, and I’m going to oversimplify some of the legal principles. But if you’re curious how the sausage is made, read on.