Kansas City, Mo ? An appeals court on Monday reinstated the conviction of a Mission Hills, Kan., attorney accused of using an Internet chat service to solicit sex from someone he believed to be a 14-year-old girl.

A federal jury last summer convicted Jan P. Helder of using the Internet to attempt to entice a child into sex. But minutes later, U.S. District Judge Dean Whipple in Kansas City dismissed the verdict, siding with defense attorneys who said that Helder couldn’t be guilty because the person he communicated with online was actually an undercover Platte County detective, not a minor.

The decision outraged online protection advocates who worried it would sideline similar investigations and led some members of Congress to propose changing the law to prevent future defendants from pursuing a similar defense.

The 8th U.S. Circuit Court of Appeals in St. Louis, however, joined with at least three other federal circuits that have upheld such convictions, saying the importance is that Helder thought he was seducing a minor, not whether the minor truly existed.

“We hold that an actual minor victim is not required for an attempt conviction,” the court wrote, drawing parallels to prostitution stings in which undercover officers pose as prostitutes.

The three-judge panel sent the case back to the lower court for sentencing. Helder faces a prison sentence of between five and 30 years.