Financial trader Michael Coscia was sentenced Wednesday in Chicago to three years in prison for “spoofing,” providing the first glimpse of the teeth behind an anti-manipulative trading law passed in 2010.

Prosecutors hailed the prison term in the first criminal spoofing case as a signal that commodities markets are fair, and they want the punishment to serve as a deterrent to future manipulative trading. Coscia’s defense lawyers at Dentons and Kobre & Kim promised to appeal the conviction and challenge the law, which defines “spoofing” as the placement of an order to buy or sell futures contracts without the intent to execute the trade.