25 CFR § 573.2 - When may a letter of concern be issued?
(a) Prior to the Chair taking an enforcement action, a letter of concern may be provided by NIGC staff, detailing concerns regarding compliance with the Act, this chapter, or any tribal ordinance or resolution approved by the Chair under part 522 of this chapter. A letter of concern describes the available facts and information, includes a preliminary assessment regarding the incident or condition, and indicates that it may be a violation.
(b) Action under this section does not constitute agency action.
(c) A letter of concern issued under paragraph (a) of this section must provide a time period for the respondent to respond. If the letter of concern is resolved without enforcement action, NIGC staff may send an investigation completion letter pursuant to § 571.4 of this chapter.
(d) The Chair's discretion to take an enforcement action is not limited or constrained in any way by this section. When the Chair takes enforcement action before a letter of concern is issued, the enforcement action must state the reasons for moving directly to an enforcement action without first issuing a letter of concern.