Here is a situation that comes up more often than you would think. Imagine you work as a home health aide. You look at the visit records and you think the company is illegally billing for visits that nobody made. You tell your supervisor you believe that is illegal. The company looks into it. It turns out you were wrong. The visits happened. The paperwork was just entered late. A month later, you are fired.
A lot of workers in that spot assume they have no case. They spoke up, they got it wrong, and now they feel foolish for saying anything. California law does not work that way. Labor Code section 1102.5(b) says your employer cannot retaliate against you for reporting something you had reasonable cause to believe was a violation of a state or federal law, or a violation of or failure to follow a local, state, or federal rule or regulation. The test is what you reasonably believed when you spoke up. It is not whether you turned out to be right.
The law covers your report whether you make it to a government or law enforcement agency, to a person with authority over you, to another employee who has authority to investigate, discover, or correct the problem, or to a public body running an investigation, hearing, or inquiry. It protects you even when reporting problems is part of your job. It also protects you when your employer only believes you reported something, or believes you might.
This example is made up. The rule is not. In California, being wrong is not the same as being unprotected, and what matters is what you had reasonable cause to believe when you spoke up. (Lab. Code section 1102.5(b).)
Source: https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=LAB§ionNum=1102.5