For years, New York Attorney General Letitia James pointed to the numerous lawsuits her office brought against ex-President Donald Trump's administration, filing legal challenges over a variety of policy matters ranging from the environment to immigration. 

She even touted the busy casework in her campaign video during her short-lived bid for governor earlier this year. 

"I've sued the Trump administration 76 times," she said. "But who's counting?"

On Monday, it was Trump's turn to file a lawsuit of his own. The former president sued to halt the attorney general's probe of his company, an investigation stemming from whether Trump inflated the value of his real-estate holdings.

Trump in a statement said "This is not about delay, this is about our Constitution!" and accused James of doing the bidding of the Democratic Party. James in her own statement said the lawsuit won't stop her investigation. 

"To be clear, neither Mr. Trump nor the Trump Organization get to dictate if and where they will answer for their actions," James said. "Our investigation will continue undeterred because no one is above the law, not even someone with the name Trump." 

Former criminal prosecutor Dan Schorr said it's unlikely the legal challenge will be successful, calling the move a unusual approach to stop an investigation. 

The lawsuit deals with statements she's made before and that's not going to lead a federal court to tell her she can't be involved in these investigations," he said in an interview. 

But the suit rasies broader questions over how prosecutors talk about the targets of their investigations. James has been deeply critical of Trump over the years and had campaigned on a pledge of being a counterweight to his administration. 

"I think it's important that prosecutors not base their decisions on the political winds or who their political opponent is," Schorr said. "And even if they're not basing it on that, it's important public perception is they're not basing it on that."

Trump himself, of course, has made his own statements about imprisoning critics. 

"Donald Trump as president was talking about locking up his political opponents, so certainly he's not someone whose appauled by this behavior when he's done similar things," Schorr said.  

The civil investigation is just one probe Trump faces in New York. Manhatttan DA Cy Vance has opened a criminal investigation as well. Both investigations have been well known in the public. 

So why file the lawsuit now? Civil investigations can be damaging to business interersts. Then there's the matter of Trump's own ambitions in future elections. 

"Filing a suit like this is often a big fundraising tool for politicians because then they can send out an email blast saying I'm suing the attorney general, donate to support it," Schorr said. "You see that a lot with politicians."