If you can’t condone your client’s behaviour then you have to act.

Q: One of my clients is doing some international business that's borderline illegal and definitely unethical. I spoke with my boss, but he dismissed my concerns. I'm afraid that if I escalate this, it will have negative ramifications for my career as my boss will lose trust in me (and I report only to him). I'm also afraid that if I don't follow up, there is a possibility, however remote, that we'll all go to jail or be subject to bad publicity. What's my next move?

A: How certain are you that what your client is doing is legally wrong? Have you consulted an attorney, either inside or outside your company? Consider the issue from a global perspective: is the action considered legally or ethically wrong in the country where it’s happening? Or is it a standard practice within the industry that might not bear scrutiny elsewhere? 

These questions must be answered before you take steps that are irrevocable and could damage your standing within your organization. 

Next, research online any governmental whistleblower protections, which vary by country and by industry. Make certain to use a computer or mobile device that you own, rather than your work computer or network. You should consider documenting every interaction you have with your boss, your client, and anyone else in which you raise this issue. Print out your emails on the topic, or forward them to your personal email account if your company policy allows you to do so. If you end up in the middle of a court case or an employment arbitration hearing, you’ll be glad to have these documents.

Consider your boss’s initial response carefully. You know that your boss “views the behaviour as acceptable or is unconcerned about acting unethically,” since your attempt to raise the issue went nowhere, said Maurice Schweitzer, a professor at the University of Pennsylvania’s Wharton School who studies business ethics and negotiations. To judge whether you’re reading the situation correctly, he recommended consulting a few senior figures in your industry – anonymously, if possible. 

If they agree that you can’t condone your client’s behaviour or be involved in it, then you have to act. At this point, it’s time to go back to your boss’s office.

“You should let your boss know that being a party to this behaviour crosses the boundary for you, and you should propose a remedy,” Schweitzer said. If your boss doesn’t take you seriously this time, you’ll need to go higher in the organization. Hopefully, you have a more senior mentor you can ask for guidance. If not, confidentially approach a top executive with a reputation for honesty.

You’re right that this isn’t likely to end well for you in terms of your relationship with your current boss. But you have to preserve your own principles and reputation, as well as your 

Career — even if you lose this job or are forced to quit. Think of the broader picture, said. Schweitzer, “It is much harder to find a new job after you have been convicted of illegal behaviour.”

Work Ethic is a twice-monthly column on BBC Capital in which we consider the ethical and interpersonal dilemmas that workers face around the world. We welcome knotty questions from readers at workethic@bbc.com.