In an effort to curb the growing number of measles cases, New York City Mayor Bill de Blasio declared a health emergency for the borough of Brooklyn and will require unvaccinated individuals to receive proper measles immunizations. 

A group of parents, however, have decided to push back against this.

The lawsuit the group filed against New York City’s Department of Health claims the order is "arbitrary and capricious" and the measure itself as "drastic."

The order filed under the emergency declaration would require anyone, starting at the age of 6 months, who lives, works, or attends school within the Brooklyn neighborhood of Williamsburg to be vaccinated. De Blasio called the measles outbreak a "very serious situation" gripping the city.

Brooklyn and Queens have had 285 confirmed cases of measles since October, according to the CDC.

Part of de Blasio’s reasoning for the order is because of the area's large Orthodox Jewish population and with Passover beginning Friday. The holiday means it will be a heavy travel period to and from Israel, which has been battling its own measles outbreak. De Blasio said this order is "to make sure it is a good holiday we have to ensure that people are protected."

The parents' efforts are the latest in a series of countersuits. A group of parents from Rockland County, New York, filed a lawsuit after their children were barred from attending school because they were unvaccinated.