The earliest whistleblower cases document corporations explicitly retaliating against employees who file their concerns internally. Furthermore, in these cases, the corporations argued in court that they could fire at-will employees who report concerns internally. Corporations have won and prevailed in many of these cases.
Most recently, the U.S. Supreme Court backed the Chamber of Commerce and held that employees who report internally lack any protection from retaliation under the Dodd-Frank Act. In response to the assault of corporations against whistleblowers who report internally, Congress amended and enacted laws to protect employees who report internally.
Given the long history of retaliation against internal whistleblowers, and the opportunity to obtain a reward if you contact the appropriate government agency, no employee should ever report an allegation of fraud or corruption internally until he or she has contacted an attorney and obtained advice. Furthermore, if an internal compliance program is managed by company attorneys, that program should be avoided.