I think that the line is drawn when your decision either puts your childs life in danger or puts other children in jeopardy. Going off of your example, if you choose not to immunize your child, thats fine, but if you make that choice it is your responsibility to not allow your child anywhere near anyplace where a child who is to young to be vaccinated may be, that means no public playgrounds, daycares, restaurants, etc. If you do not do that and put others children in jeopardy by exposing them to a preventable life threatening disease, then I have a huge problem with what your doing. Many parents who dont vaccinate say "oh, I simply wont take them out when they are sick", thing is the majority of diseases are contagious before they show symptoms and the children who are too young to be vaccinated are the ones who are most at risk for complications or death from disease, so if you take your unvaccinated five year old out, and he has the measles but you dont know it yet, he could easily give it to an infant who is too young to be vaccinated and they could die because of your choice. Theres a line between making a choice that works for your family and pure irresponsibility.