Measles is back, and so are difficult conversations about childhood vaccinations.

Pennsylvania is experiencing its worst measles outbreak in three decades, with 232 cases reported across 18 counties as of early August and more than two dozen cases in the Philadelphia region. About 35% of the state’s cases have involved children, and public-health experts are worried that the numbers could spike as schools reopen.

The resurgence is part of a larger national outbreak. The United States recorded more measles cases in the first seven months of 2026 than in all of 2025, putting the country at risk of losing the measles-elimination status it achieved in 2000. Falling vaccination rates have left more communities vulnerable to a disease that is extraordinarily contagious and can spread even before someone realizes they have been exposed.

The American Academy of Pediatrics recommends two doses of the MMR vaccine before kindergarten, a series that protects about 97% of children, according to federal data. Notably, none of the recent measles cases in Pennsylvania involved a vaccinated individual.

But what happens when co‑parents disagree about vaccines? Some parents worry about side effects, others question vaccine safety, and many are influenced by misinformation. These disagreements can become especially challenging when parents share legal custody and must jointly make medical decisions for their child. A recent Pennsylvania family law case illustrates how courts may approach these disputes.

In Marra v. Jacobs, parents shared legal custody but strongly disagreed about routine childhood vaccinations. The mother wanted the child to follow the standard immunization schedule recommended for school-aged children. The father, who described himself as “vaccine‑hesitant,” opposed vaccinating the child, citing concerns he found online but offering no medical or expert testimony to support them.

Because the parents reached an impasse, the issue went before the court. In its final custody order, the trial court maintained shared legal custody but granted the mother specific authority to make decisions about state‑mandated and school‑required vaccinations. The court reasoned that assigning this limited authority to one parent would reduce ongoing conflict and ensure the child could meet school requirements.

A key part of the court’s reasoning involved what is called “judicial notice,” the ability of a judge to accept certain facts as true without requiring formal proof when those facts come from sources whose accuracy cannot reasonably be questioned. Here, the court took judicial notice of vaccine guidance from the Centers for Disease Control and Prevention, recognizing the CDC as a reliable authority on vaccine safety and effectiveness.

This approach is significant as, in many past cases, parents supporting vaccination have traditionally had to present expert testimony to establish that vaccines were safe and medically appropriate, often leading to costly “battle of the experts” hearings. By treating CDC guidance as an accurate source, the court removed the need for competing medical experts and streamlined the process.

Ultimately, the court concluded that following standard medical recommendations and complying with school vaccination requirements served the child’s best interests, particularly because there was no evidence of a medical condition that would make vaccination unsafe. The father’s philosophical objections alone were not enough to outweigh those considerations.

As a result, Marra v. Jacobs has become an important reference point in family law matters involving vaccination disputes. The ruling suggests that courts may increasingly rely on established public‑health guidance when evaluating a child’s best interests in custody cases.

If you would like to talk to a top Bucks County family law attorney regarding custody issues that are approaching contentious status, we can help. Contact Williams Family Law at 215-340-2207, or email us at info@bucksfamilylawyers.com.