Former U.S. President Donald Trump’s two eldest children have been subpoenaed by New York authorities probing whether his real-estate business manipulated the value of key assets for tax and insurance purposes.

Ivanka Trump and Donald Trump Jr., longtime business associates of their father, on Monday night filed a joint motion in New York state court to block the subpoenas, accusing New York Attorney General Letitia James of making an unconstitutional attempt to get testimony from the family members while they still face a separate criminal investigation.

James had revealed the existence of the subpoenas in a court filing earlier on Monday, saying she anticipated a motion to block them. Donald Trump is also fighting an earlier subpoena, she said.