Nick Wilde: It's called a hustle, sweetheart.
Nick Wilde: Everyone comes to Zootopia, thinking they could be anything they want. But you can't. You can only be what you are. Sly fox. Dumb bunny. And that is not wet cement.
Judy Hopps: Life's a little bit messy. We all make mistakes. No matter what type of animal you are, change starts with you.
Chief Bogo: Life isn't some cartoon musical where you sing a little song and all your insipid dreams magically come true. So let it go.
Chosen answer: Finnick didn't say anything that could be used against him and she had no proof that he was delinquent on his taxes, as he said, "She hustled you good!"
Finnick was involved in all of Nick's scams so shouldn't he have been charged as an accessory and therefore also forced to help Judy?
Nick's crime was not paying taxes. Judy had no evidence that Finnick was guilty in any tax evasion or that he even participated in earlier scams.