"The officers made a good faith, but mistaken effort to enforce an old unwritten interpretation of the prohibitions about demonstrating in the Capitol," Capitol Police Chief Terrance Gainer said in a statement late Wednesday.
"The policy and procedures were too vague," he added. "The failure to adequately prepare the officers is mine."
The extraordinary statement came a day after police removed Sheehan and Beverly Young, wife of Rep. C.W. "Bill" Young, R-Fla., from the visitors gallery Tuesday night. Sheehan was taken away in handcuffs before Mr. Bush's arrival at the Capitol and charged with a misdemeanor, while Young left the gallery and therefore was not arrested, Gainer said.
"Neither guest should have been confronted about the expressive T-shirts," Gainer's statement said.
Gainer added that he was asking the U.S. attorney's office to drop the charge against Sheehan. The statement also said he apologized to the Youngs and "share the department's plans for avoiding this in the future."
When Young was told she was considered a protester, she called the police officer an idiot, but unlike Sheehan, was not arrested, reports CBS News correspondent Bob Fuss.
"A similar message has been left with Mrs. Sheehan," Gainer said.
For his part, Bill Young said he was not necessarily satisfied.
"My wife was humiliated," he told reporters. He suggested that "sensitivity training" may be in order for Capitol Police.
A foreign-born American citizen who was the guest of Rep. Alcee Hastings, D-Fla., also was taken by police from the gallery just above the House floor, Hastings said Wednesday.
The congressman met with Gainer and said he also requested a meeting with House Speaker Dennis Hastert, R-Ill., about the incident.