A U.K. employment tribunal’s ruling that a former BP employee was not entitled to whistleblower protection has shone a spotlight on the legal issues workers must consider ahead of speaking up.

Jonathan Zarembok claimed he was fired as a trader at the oil company after raising concerns bribery and corruption was taking place in Nigeria through use of local agents and their dealings with state oil company NNPC.

The tribunal ruled last month Zarembok’s claims did not amount to “protected disclosures” because his concerns “did not tend to show that any wrongdoing was likely rather than merely possible.”