California’s Constitution spells out the right to a free public education, and lawmakers have fortified that guarantee over the years by safeguarding students against discrimination and inequality in the classroom. But now a debate over that protected access to an education has surfaced in the most contentious legislative battle in Sacramento this year: Does one student’s right to an education trump another student’s right to stay healthy? That question looms over Senate Bill 277, a controversial proposal that would tighten the requirements that all children be vaccinated to attend a California school.