Mayor Bill de Blasio is calling the measles outbreak a public health emergency, but one lawyer disagrees and is vowing to fight for residents who choose not to vaccinate their kids.

Mayor de Blasio is taking action by requiring Brooklyn residents living in certain zip codes to get vaccinated or face fines.

Lawyer Michael Sussman calls the mayor's plan executive overreach and says the rules are forcing people to go against their religion.

"My hope is we have a rational, reasonable discussion," says Sussman. "We don't call something an epidemic, which is not an epidemic. We don't scare people. It's up to a judge how fast he or she can hear the matter and dispose of the matter."

Neighborhoods with a large Orthodox population like Williamsburg could face fines of up to $1,000 for failing to vaccinate their children.

Officials say the city health department will try to interview Williamsburg residents diagnosed with measles and everyone they have come in contact with.

Mayor de Blasio says he is confident that the city's vaccination order will pass any legal challenge.