The news about both Dominique Strauss-Kahn and Arnold Schwarzenegger has brought renewed attention to what seems like a myriad of past allegations of sexual harassment by the two politicians. Strauss-Kahn and Schwarzenegger have also both now acknowledged relationships with women who worked for them.

So, when something happens between a boss and employee, where’s the line between harassment and a consensual relationship? It turns out the law isn’t as clear as you might think.

In the United States, certain situations are considered inherently coercive. For instance, sexual contact between prison guards and inmates—even if it’s entirely consensual—is sexual abuse by definition. However, laws governing the workplace are far more permissive, though companies may adopt their own, more stringent policies. 

Under U.S. federal anti-discrimination law, sexual advances or comments in the workplace aren’t necessarily against the law, and that’s even if there’s a big power gap at play, Ernest Haffner, a senior attorney at the government’s Equal Employment Opportunity Commission, told me.

“If that were true, a romantic relationship could never be consensual or welcome in a particular workplace,” Haffner said. “I don’t think case law supports that.”

Instead, the test is whether the sexual comments or conduct was unwelcome. Sound simple? Not so fast.

Experts say there aren’t hard-and-fast rules for judging whether conduct is unwelcome. “Unwelcomeness is tricky,” said Haffner. “The person may subjectively believe that the conduct is unwelcome, but you have to objectively be able to show it.”

In some cases, a person may be able to show that advances were unwelcome even though he or she didn’t protest or say so at the time. “Consensual” isn’t the same thing as ”welcome,” experts say. It all comes down to a close analysis of any given situation.

Lawyers told us that power dynamics can be a factor. Past history between the two people can also be a factor. Even body language can be a factor.

“The bright line is it being unwelcome, but the facts that make that up are really going to depend on the circumstances,” said Fatima Graves of the National Women’s Law Center, noting that courts have ruled differently. “Some courts have said that it’s important for the employee to communicate clearly that it is unwelcome,” Graves noted.

That’s why the government and anti-discrimination groups encourage people who believe they’re being harassed to inform the harasser directly that the advances, comments or conduct are unwelcome. Legal Momentum, a women’s rights group, warns the targets of harassment, “Your legal claims can be hurt if you keep silent.” It also provides a sample letter [PDF] to send to a harasser, suggests reporting the harassment to the company and recommends holding on to all records documenting the harassment itself and complaints about it.

Once it’s established that the conduct was sexual harassment, it’s up to the company to prove that it’s not liable. If the harasser was in a supervisory role, the company is almost always liable, though companies can try to argue that the person didn’t make use of internal channels to report the harassment or waited too long to do so.

Under U.S. anti-discrimination law—civil statutes—there are caps on how much companies can be forced to pay if the case goes to trial. They’re based on the size of the company—and awards for even the largest companies are capped at $300,000, though this doesn’t include compensation for, say, medical or therapy expenses incurred as a result of the harassment.

More often than not, however, these cases will settle out of court. President Bill Clinton famously paid Paula Jones $850,000 to make her sexual harassment lawsuit go away, with no apology or admission of guilt needed on Clinton’s part. Just last year, former Hewlett-Packard CEO Mark Hurd settled for an undisclosed amount a sexual harassment claim brought by a company contractor.

Not all workers in the United States are covered by federal sexual harassment laws, however. The housekeeper with whom Schwarzenegger fathered a child out of wedlock, for instance, most likely was not.

“You have to have so many employees before you’re covered,” said Michelle Caiola, a senior attorney at Legal Momentum who previously worked for the government’s EEOC. “Being an employer of one person in a household—that wouldn’t be covered.”