COLUMBIA -- South Carolina Gov. Mark Sanford's lawyer says a handwritten note on a 1987 letter justifies high-priced travel for the disgraced chief executive and puts him in line with routine practices involving Commerce Department economic development trips.

Meanwhile, Sanford chief counsel Swati Patel sent letters to the presidents of Clemson University, the Medical University of South Carolina and the University of South Carolina asking them to produce records showing how and when they use planes they own.

Those letters, sent Tuesday, come after weeks of scrutiny of Sanford's travel and spending practices that started after he disappeared from the state for five days in June. When he came back, he revealed an affair and reimbursed the state for costs tied to a trade trip that landed in him Buenos Aires, where he began his affair with Maria Belen Chapur.

The State Ethics Commission is investigating issues raised by Associated Press investigations of Sanford's commercial travel, personal and political use of state aircraft, and undisclosed use of private planes. Legislative leaders are waiting for the results of the investigation before taking action that could include bringing the Legislature back into session for impeachment proceedings.

State Sen. David Thomas has been investigating Sanford's practices, too, and asked Sanford's office to document how he has used commercial flights.

Patel said Sanford's use of commercial planes "complies with applicable travel laws and regulations." She based that conclusion on a June 16, 1987, letter to then-Comptroller General Earle Morris with a handwritten note in upper left hand corner. It reads: "Approved by Mr. Morris 6-22-87" with "business class travel, for director and chairman only" underlined. It did not mention anything about the governor getting that treatment.

Patel argues that approval is key, since Morris drafted the travel regulations. His agency's "interpretation of its own travel regulations proves that commerce has authority to purchase business class seats for foreign travel under the travel regulation," Patel wrote.

If Sanford and Commerce planned to routinely use pricey tickets, they should have gone to the Legislature to change the law or a court to get the law and regulation invalidated, Thomas notes. Instead, "the wrongdoing is uncovered and they're falling all over themselves to find some way to absolve themselves of the wrongdoing," he said.

Morris, who left office in 1999, was not available. He was convicted in 2004 of 22 counts of securities fraud and is serving a state prison sentence and scheduled for release in April.

J. Mac Holladay, who ran what was then called the State Development Board, was traveling Wednesday and did not immediately respond to messages.

"That's something I'd have to research," said Jim Holly, chief of staff for the current comptroller general. "I have no reason to believe it's not an accurate representation."

State regulations that have the force of law say: "Travel by commercial airlines will be accomplished in coach or tourist class, except where exigencies require otherwise."

Commerce spokeswoman Kara Borie said those exceptions were used because there were overnight flights, schedules were demanding and confidential information was reviewed during flights. "From our perspective, we believe the purchase of business class tickets was appropriate," Borie said.

A review of eight itineraries for Commerce trips Sanford took between 2003 and this year shows only one instance of Sanford having to immediately go to work after an overseas flight. In one case, there was a 12-hour gap between his arrival and a dinner. The rest involved meetings scheduled the following day or later.

There is no routine review of whether an agency is abusing the exceptions.