This article offers practice tips regarding the use of expert testimony in cases pitting one parent's wish to have a child vaccinated for COVID-19 pursuant to the FDA's emergency            authorization of the Pfizer-BioNTech vaccine for children in certain age ranges and the CDC's recommendation that children in those age ranges be vaccinated against the other parent's  objection where the parents have shared legal custody of the minor child.

• Hire an expert, do not assume that evidence crucial to the case can be admitted through a fact witness.

Unless a judge has signaled in pretrial proceedings that judicial notice will be taken of the FDA's emergency authorizations for having children in certain age ranges receive the Pfizer-BioNTech vaccine and of the CDC's recommendations that children in those age ranges be vaccinated, failure to call an expert is potentially fatal to the party seeking to have the child vaccinated. A fact witness' testimony as to the FDA's authorization and the CDC's recommendation is subject to a hearsay exception, and there is no guarantee that the court would overrule the objection based on the public records exception to the hearsay rule. The better and admittedly more expensive practice is to retain an expert, thereby assuring that the most important evidence that the vaccine is safe are admitted. In a case tried by the author, the party seeking to have the child vaccinated retained an expert who was able to testify to the FDA's authorization and the CDC's recommendation without objection.

• Don't assume that the child's physician will testify.

Ideally, a child's pediatrician would serve as the expert witness for the party seeking to have the child vaccinated. The pediatrician is knowledgeable about the child's health history, including prior vaccines, and, presumably, will have recommended the vaccine. However, in a case tried by the author, the child's pediatrician declined to testify, explaining that her clinical duties were paramount. That decision turned out to be consistent with anecdotal input that medical practices in general discourage physicians from giving testimony even for their own patients.  Issuing a subpoena to a pediatrician who is reluctant to testify could jeopardize the doctor-patient relationship and risks less-than-friendly testimony. Better to hire an outside expert.

• Learn the basis for the objection before retaining an expert. 

Parties seeking authorization for the vaccine may be compromised at trial if they do not learn the basis of the other side's objection to the vaccine in time to retain an expert who can address that objection. Unlike, say, dueling mental health evaluations of a parent in a custody case where both sides' experts have similar expertise and can be expected to cover the same general ground, the vaccine for children implicates a wide range of expertise, including endocrinology, pediatrics, virology, immunology and pharmacology. Other areas of specialized knowledge such as vaccine development and regulation may also come into play. No individual expert will be able to cover all of these bases.