here's the criminal sanctions ...
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http://www.fourmilab.ch/ustax/www/t26-F-75-A-I-7213.html>
Federal employees and other persons
It shall be unlawful for any officer or employee of the United States or any person described in section 6103(n) (or an officer or employee of any such person), or any former officer or employee, willfully to disclose to any person, except as authorized in this title, any return or return information (as defined in section 6103(b)). Any violation of this paragraph shall be a felony punishable upon conviction by a fine in any amount not exceeding $5,000, or imprisonment of not more than 5 years, or both, together with the costs of prosecution, and if such offense is committed by any officer or employee of the United States, he shall, in addition to any other punishment, be dismissed from office or discharged from employment upon conviction for such offense.
... and here's the Wilsons' civil action ...
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http://www.fourmilab.ch/ustax/www/t26-F-76-B-7431.html>
In general
(1)
Disclosure by employee of United States
If any officer or employee of the United States knowingly, or by reason of negligence, discloses any return or return information with respect to a taxpayer in violation of any provision of section 6103, such taxpayer may bring a civil action for damages against the United States in a district court of the United States.
(2)
Disclosure by a person who is not an employee of United
States
If any person who is not an officer or employee of the United States knowingly, or by reason of negligence, discloses any return or return information with respect to a taxpayer in violation of any provision of section 6103, such taxpayer may bring a civil action for damages against such person in a district court of the United States