An arbitrary decision means making a choice or judgement without any specific reason or logic behind it. It is a decision that seems random or lacks a clear and fair basis for being made. Full definition
They put posters up, and they make arbitrary decisions about what's going to make people happy. (canadianbusiness.com)
How many drivers will not be eager to share driving info with insurers and others either for privacy reasons or skepticism about what arbitrary decisions about them will be made based on that info? (slaw.ca)
Because of all these opportunities for arbitrary decision, only a small number of those convicted of capital crimes are actually executed. (religion-online.org)