Uh... OP. Click your link and read it.

(1) Inspection or disclosure by employee of United States

If any officer or employee of the United States knowingly, or by reason of negligence, inspects or 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) Inspection or 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, inspects or discloses any return or return information with respect to a taxpayer in violation of any provision of section 6103 or in violation of section 6104(c), such taxpayer may bring a civil action for damages against such person in a district court of the United States.

TL:DR: If you inspect or release somebody else's tax returns and that person has violated certain US codes then that person is allowed to sue for damages.

It is not a "federal crime". This is a law describing a circumstance under which you can initiate a civil action (i.e. a lawsuit) for having your tax information leaked.

Fucking jackass OP.