In the movie Blue Jasmine by Woody Allen, Jasmine slept with Dwight without telling to Hal and they broke up.
And she comes to Hal for accusing his relationship with a teenage girl, calls to the FBI and cuffs him.
Why did Jasmine arrest Hal?
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I'm afraid you completely misunderstood a lot of the movie.
At the start of the movie, Hal is already dead (killed himself in prison). Those scenes with Hal (mostly in New York) were all flashbacks.
The present is with sister in San Francisco. Jasmine meets Dwight at a party in San Francisco. This is long after Hal killed himself.
But to your question: "Why did Jasmine arrest Hal?" It was purely a spur of the moment, revenge thing. Hal had just told Jasmine that he was in love with this French girl and was going to leave her. And almost immediately, Jasmine calls the FBI (or rather calls someone to get the FBI's number).
I didn't watch the movie, but according to the plot summary in the movie Wikipedia page, he was arrested for committing fraud.
Hal is reported to the authorities as a major fraudster who has lost a lot of money raised from many investors, including Ginger (Jasmine sister) and Augie.