The Transportation Security Administration investigated KCTV5 News for exposing what some experts called a serious flaw in airline security.

Last year, KCTV5 News was able to board flights to Washington and Chicago using IDs the station created.

Document checkers at Kansas City International Airport and Washington Dulles International Airport glossed over the homemade ID.

One airline screener couldn't tell if the ID was real or not, but he let an undercover producer through anyway, and the producer headed off to Washington.

Since then, the TSA took over document checking at KCI.

So earlier this year, KCTV5 News decided to try to fly again with the homemade ID.

That time, a TSA screener questioned the undercover producer and said he had to have a government-issued ID to fly.

Technically, that's not true.

On the TSA's Web site, the policy "recommends" that ID be carried, but there's never been a public law requiring it, and after a secondary screening, the undercover producer was able to catch a flight to Chicago and back.

A month later, the president and CEO of KCTV5's parent company received a letter from the TSA informing the company that KCTV5 was being investigated for using "homemade photo identification" in an attempt to "circumvent required additional security measures and procedures."

It's an accusation attorney Jim Harrison finds especially interesting given there is no rule requiring any ID whatsoever to board a plane.

"TSA is not necessarily looking for weapons or explosives. They're using our transportation network as a dragnet for law enforcement," Harrison.

Harrison argued a lawsuit against the government that would have forced it to reveal the source of the so-called ID requirement, but that lawsuit was dismissed -- in part, Harrison said, because the regulation requiring ID is shrouded in secrecy.

"They designated it SSI, or sensitive security information, and said the release of which would be detrimental to the safety of transportation," Harrison said.

According to court documents, the details of the SSI shall only be disclosed on a "need to know" basis.

In effect, TSA is saying people are required to abide by laws but people aren't allowed to know what those laws are.

"One of the problems is that TSA's own security personnel don't understand what the law is because the law seems to be so secret that TSA will keep it from their employees," Harrison said.

In fact, many people don't realize the origin of the so-call ID requirement didn't follow a terrorist attack.

In 1996, 230 passengers were killed when TWA Flight 800 exploded midair.

On July 18, 1996, then-President Bill Clinton said, "While we seek the cause of the disaster, let us all agree that we must not wait to alleviate the concerns of the American people about air safety and air security."

To address those concerns, according to former counter-terrorism adviser Richard Clarke, new airline security measures were introduced by the Clinton administration, and the so-called requirement to present "government-issued photo ID" became a staple at U.S. airports.

More than 10 years later, the TSA says security personnel are required to request ID but government ID is not required to fly.

"The best form of Homeland Security is liberty and for the people to exercise that liberty, and when you start curtailing that liberty in the hopes of providing more security, then you're just asking for trouble," Harrison said.

Late Wednesday afternoon, the TSA sent KCTV5 News a statement calling the station's investigation "irresponsible" and a "disservice to passengers." Nevertheless, KCTV5 News was told that the TSA completed its investigation and decided not to take action against KCTV5 for the story.

The TSA said new regulations are expected to go into effect later this year.