Employees of the Executive Branch are subject to a number of criminal statutes and related regulatory provisions, including those of 5 C.F.R. Part 2635 which sets forth Standards of Ethical Conduct. These standards and a summary of them may be found via the following link to the United States Office of Government Ethics:
The documents below contain additional information on conflicts of interest, disqualifications, and recusal.
Word About Ethics (textual descriptions)
Ethics At A Glance (graphical depictions)