A traveler undergoes an enhanced pat down by a Transportation Security Administration agent at the Denver International Airport on November 22, 2010 in Denver, Colorado. (John Moore/Getty Images)

SAN FRANCISCO (KPIX 5) – Showing a government-issued identification at a Transportation Security Administration checkpoint is a practice most travelers consider part of the flying experience. However, it is not mandated by federal law.

A KPIX 5 investigation reveals that passengers can pass through security checkpoints using a broad range of documentation including utility bills, prescriptions, credit cards, and even Costco membership cards – a fact that surprises veteran travelers.

“I mean I’m about as vanilla as can be and I am being patted down,” commented Patrice Culligan who was catching her flight from SFO to Washington D.C. and has been the subject of rigorous security measures even after she had provided government identification at the security checkpoint.

“Its about validating who you are so if it’s a library card or a Costco card or a school ID, they are all not forms of government identification, but at least it is something that is printed with your name on it,” said TSA spokesman Nico Melendez.

Melendez adds those who do not have government ID should expect a secondary screening, which could include swab tests and inspection of their carry-on baggage.

A KPIX 5 undercover producer tested this security system, arriving at the San Francisco, San Jose and Oakland airports without official documentation. In every case, the producer was allowed to pass through security using a student ID and personal credit cards and was not subject to a secondary screening before gaining entrance to the terminal.

At the San Francisco and Oakland airports, the producer was asked by TSA agents whether she had a Costco card that she could show them.

When the producer went to the Oakland airport for a second time without a wallet or any form of documentation at all, she was brought to the side of the security line to answer additional questions but less than twenty minutes later, she was allowed to proceed to her flight.

Independent aviation security experts worry this policy that gives a lot of discretion to agents poses a security risk. “Every time you time you introduce a vulnerability, our adversaries are going to take advantage of that,” said Billie Vincent, former director of the Federal Aviation Administration Office of Civil Aviation Security.

Vincent said that Congress could improve the process by making official identification required for travel, but that the political climate in Washington shies from ID requirements whether it is for voting or traveling. “It is very difficult to get some things done absent disaster,” said Vincent.

But TSA officials are more confident and believe the identifications can only provide a certain level of security. They point to other forms of security that take place before check-in as more meaningful, calling the physical checkpoints the last but certainly not the most important step on the road to safety.

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