"This could eliminate any question as to strict criminal liability offenses being actionable, and would reintroduce to federal criminal law the fundamental and venerated principle that a criminal offense must include proof of intent to do a bad act," said Terwilliger , a former deputy attorney general under the George W. Bush administration.

Congress could accomplish this by passing one overriding law that requires proof of intent for any federal crime in which mens rea is not currently a requirement, George Terwilliger, a partner at Morgan, Lewis & Bockius, testified during a hearing on Capitol Hill.

A panel of four attorneys told members of Congress today that one way to fix the nation's bloated and convoluted criminal code is to require prosecutors to prove intent, especially when it comes to regulatory violations.

This is something that Congress already appears to know. The House Judiciary Committee formed a task force to tackle this overcriminalization, and called on Terwilliger and the other lawyers to tell them how.

Some examples of obscure criminal laws that representatives brought up Friday: A child who saved a woodpecker from her family’s cat was fined $535 under the migratory bird law, and a 66-year-old retiree who went to prison because he didn't have proper paperwork for orchids.

"The recent growth of the federal code in all areas of life has brought with it an ever-increasing labyrinth of federal regulations, many of which also impose criminal penalties without a showing of mens rea, or criminal intent," judiciary committee chairman Representative Bob Goodlatte (R-Va.) said Friday.

The code has been gaining criminal statutes "at a rapid rate, about 500 a decade," Goodlatte has said. The code is up to some 4,500 crimes.

The task force staff asked the Congressional Research Service to update the calculation of criminal offenses in the federal code, which was last undertaken in 2008, said task force chairman Representative John Sensenbrenner (R-Wis.)

"CRS's initial response to our request was that they lack the manpower and resources to accomplish this task," Sensenbrenner said Friday. "I think this confirms the point that all of us have been making on this issue and demonstrates the breadth of overcriminalization."

John Malcolm, a senior legal fellow at the conservative Heritage Foundation, testified that the federal government should be required to identify every federal crime and post it in a manner that is easily accessible to the public at no cost.

"The criminal code today is so vast and complex that judges and lawyers have a lot of trouble discerning what's legal and what's illegal," Malcom testified. "What hope do ordinary citizens have?"

Steven Benjamin, president of the National Association of Criminal Defense Lawyers, testified that when the average citizen cannot figure out what is illegal, "that is unfairness in its most basic form."

"We have become addicted to the use of criminal law as a blunt instrument to control social and economic behavior," Benjamin said.