Intermittently, a government agency, possibly in response to an executive order, will officially announce that some law or policy won't be enforced during some time period. Some such announcements seem to actually encourage/praise such lawbreaking (e.g., see FDA hand sanitizer example below).
Suppose I operate a business and violate such a law. If the agency later announced, "We are rescinding our non-enforcement policy. Further, we intend to prosecute violations which occurred while the non-enforcement policy was in effect."
Would a business have any protection from such enforcement?
FDA does not intend to take action against firms that prepare alcohol-based hand sanitizers for consumer use and for use as health care personnel hand rubs for the duration of the public health emergency [...]
Today, the Office for Civil Rights (OCR) at the U.S Department of Health and Human Services (HHS) announced that it will exercise its enforcement discretion and will not impose penalties for violations of the HIPAA Rules [...]