When a New York judge ruled on Sept. 26 that Donald J. Trump had committed fraud by inflating his assets, he effectively said that the heart of the case against the former president would not be subject to debate during his trial.

The civil case was brought by Letitia James, the New York attorney general, in 2022, and accuses Mr. Trump and his family business of lying to lenders and insurers about the value of their properties in order to secure more favorable terms. In a so-called summary judgment days before the trial, Justice Arthur F. Engoron of State Supreme Court in Manhattan found that they had done so — and that Mr. Trump was liable.

It is not a normal fraud case. Rather, it was brought under a powerful New York statute that gives the attorney general wide scope to investigate and prosecute corporate fraud. Because that law is being used, the questions that remain will be decided by Justice Engoron in a bench trial — one decided by a judge rather than by a jury.

Who is deciding the case?

Justice Engoron is an independent and thoughtful — if somewhat quirky — jurist who has served for 20 years in New York City Civil and State Supreme Court.

The 74-year-old judge, a former cabby with a shock of white hair and a penchant for cracking jokes from the bench, will effectively be judge and jury, deciding the fate of Mr. Trump’s New York businesses, which make up a large portion of his real estate empire.

What is the attorney general’s special authority?

A state law that dates to 1956 gives the attorney general’s office expansive authority to investigate and punish corporations. It demands a lower burden of proof than other fraud cases. Crucially, prosecutors do not have to prove that the defendant intended to act fraudulently — or that they hurt anyone financially in the process. Mr. Trump has said repeatedly that the banks he dealt with made money.

The New York attorney general’s office has relied on the law for years in high-profile cases, including against UBS, Exxon Mobil and Juul — as well as Trump University and the Trump Foundation, both of which paid millions of dollars to resolve the cases before trial.

The statute allows investigators to issue subpoenas and gather information before filing a lawsuit, often resulting in many rounds of legal back-and-forth between competing sets of lawyers.

Who might testify?

Ms. James plans to call Mr. Trump and his sons Donald Trump Jr. and Eric Trump to the witness stand. She also plans to call Mr. Trump’s daughter Ivanka to testify about the inner workings of the Trump Organization.

The attorney general submitted a list of 28 potential witnesses to the court in order of testimony. Mr. Trump is scheduled to testify second to last.

This trial will likely reunite former and current Trump Organization associates, some of whom have testified against Mr. Trump before. Notable among them are Mr. Trump’s former fixer turned chief antagonist, Michael Cohen; the former Trump Organization chief financial officer and criminal defendant, Allen H. Weisselberg; the former company controller, Jeffrey McConney; and Mr. Trump’s former accountant, Donald Bender.

For their part, Mr. Trump and his co-defendants provided the court with a list of 127 witnesses who could be called to prove their case. Their list overlaps slightly with the attorney general’s, also listing Mr. Trump himself, Donald Trump Jr. and Eric Trump, as well as Mr. Weisselberg, Mr. McConney and Mr. Bender. They may also call up to 12 expert witnesses to testify about property valuation.

What punishment might Trump face?

While Mr. Trump is not at risk of going to prison — as is possible in the four criminal cases he faces in other states — the civil trial could still produce serious consequences for the former president and his family business.

Justice Engoron already stripped the Trumps of control over their signature New York properties — a move that could crush much of the business known as the Trump Organization. Ms. James is now asking for more.

She is seeking to recover $250 million in ill-gotten gains. She wants to prohibit Mr. Trump and the Trump Organization from entering into any New York State commercial real estate deals for the next five years and to bar them from applying for loans from any New York bank during that same period.

As a final blow, Ms. James wants to permanently prevent Mr. Trump and his adult sons from running any New York companies.