The judge’s ruling in Donald J. Trump’s civil fraud case could cost him all his available cash. It also bars the former president from running a business in the state for three years.

Not only did Justice Engoron impose a three-year ban preventing Mr. Trump from serving in top roles at any New York company, including his own, but the judge also applied that punishment to the former president’s adult sons for two years. One of the sons, Eric Trump, is the Trump Organization’s de facto chief executive, and the ruling throws into doubt whether any member of the family can run the business in the near term.

But there might be little Mr. Trump can do to thwart one of the judge’s most consequential punishments: extending for three years the appointment of an independent monitor who will be the court’s eyes and ears at the Trump Organization, watching for fraud and second-guessing transactions that look suspicious.

Mr. Trump’s lawyers have railed against the monitor, Barbara Jones, saying that her work has already cost the business more than $2.5 million; the decision to extend her oversight of the privately held family company could enrage the Trumps, who see her presence as an irritant and an insult.

The judge’s ruling in Donald J. Trump’s civil fraud case could cost him all his available cash. It also bars the former president from running a business in the state for three years.

Not only did Justice Engoron impose a three-year ban preventing Mr. Trump from serving in top roles at any New York company, including his own, but the judge also applied that punishment to the former president’s adult sons for two years. One of the sons, Eric Trump, is the Trump Organization’s de facto chief executive, and the ruling throws into doubt whether any member of the family can run the business in the near term.