He was found not guilty in a criminal court on charges that he willingly evaded paying taxes. Since that day, tax protesters have used that case as their smoking gun. They're proof that they're right, and the courts have followed along and proved it too. The only problem with their argument is that Long only won his criminal trial, for which the burden of proof involved the government proving that he knew he had to file taxes. And the jury found that he sincerely did not believe that he needed to do so.

So also in civil trial, he was found guilty and he had to pay his back taxes.