Former Environmental Protection Agency Administrator Lisa Jackson will face some tough questions Tuesday when she testifies before the House Oversight and Government Reform Committee. The occasion for her appearance is the panel’s continuing investigation of executive branch abuses of the Freedom of Information Act and resistance to congressional oversight. Jackson was appointed by President Obama in 2009 and gave no indication of intending to leave the job during the 2012 presidential campaign. But she resigned suddenly in December 2012 after the EPA inspector general started an investigation of the agency’s management of official email accounts and handling of FOIA requests. It was reported Monday by the Washington Free Beacon that Jackson has since “lawyered up,” though her attorney denies that she did anything illegal.

It remains to be seen whether Jackson broke the law, but what is beyond question is that she violated the spirit of the FOIA, the landmark law guaranteeing the public’s right to see official documents (subject only to specifically enumerated exceptions such as national security). She also violated her agency’s official email policies, and the president’s commitment to run “the most transparent administration in history.”

Questions about her conduct center on her use of a fictitiously named government email account under the name of “Richard Windsor” to conduct official business. She used that email account hundreds of times to correspond with numerous officials within EPA and industry lobbyists and advocates outside the agency. After a federal court ordered EPA to release most of the Windsor emails earlier this year, the contents of many of them angered conservative critics who have long claimed the agency obstructs their legitimate FOIA requests, while favoring those from Big Green environmental activists who support the agency’s policies (and who often receive millions of tax dollars in the form of government contracts and grants).

A report released Monday by Republican members of the Senate Committee on the Environment and Public Works said that during its investigation of Jackson’s Richard Windsor email “EPA officials revealed that the agency’s FOIA office, the individuals responsible for proper administration of FOIA, may have been entirely unaware of the Richard Windsor account. Moreover, none of the EPA officials present at the briefing knew who was responsible for archiving and preserving the administrator’s emails.”

Jackson should also expect some uncomfortable questions about her use of private email accounts to conduct official business. In one of the Windsor emails the federal court ordered to be made public, Jackson asked an executive at Siemens, a major EPA contractor, to use her private email address. If Jackson tells the oversight committee that the Siemens exchange was the only one of its kind, the only way she will be able to prove it will be to share all of her private email correspondence with the panel’s investigators. If it turns out that the Siemens exchange was not unique, it could help explain Jackson’s retention of legal counsel.