Facebook CEO  Mark Zuckerberg's absence at a U.K. Parliamentary hearing on election interference and fake news drew the ire of international leaders this week—but it's not the first time a CEO declined such an invitation.

Google left its seat empty at a Senate Intelligence Committee hearing in August, after its offer to send its senior vice president of global affairs and chief legal officer, Kent Walker, was rejected, leaving some senators asking if it was because the Mountain View, California-based company was arrogant or had something to hide. The committee had asked for a CEO-level representative.

Facebook did send a representative to Tuesday's hearing—Vice President of Policy Solutions Richard Allan—but Zuckerberg's absence led politicians from some of the nine countries represented to question whether the company or its CEO took fake news seriously.

Trial and congressional hearing consultants said companies generally don't leave a CEO's seat empty unless the risks of having him or her attend outweighs the bad optics of an absence.

“They've made a risk analysis, and they determined that … the burden outweighs the benefits of having somebody show up. The burden of being reported that they're a no-show outweighs the alternative,” said Maggie Hickey a partner at Schiff Hardin and leader of its white collar defense and government investigations practice group.

Geri Satin, a senior trial consultant and co-founder at Focus Litigation Consulting, said that there may be implicit biases against CEOs that could work against them.

Companies also might not want certain words or viewpoints attributed to the CEO as a public figurehead, said corporate strategy consultant Ed Barks, who does corporate witness preparation and testimony training. He said that is why it may be better for someone other than the CEO to defend the company in a hearing.

“While the CEO clearly is the ultimate face of the company, there are times when it's best for a staff member to take the heat for a CEO,” he said.

It's also possible that the CEO may not be the most knowledgeable person on a hearing's subject. If a committee requests the CEO attend a hearing on a subject he or she isn't familiar with, it's possible a more-informed executive could be sent instead.

Barks said, if that's the case, then companies should try to negotiate with the committee and push for the more-prepared representative.

Hickey added that, if a company believes another executive would be a better choice, this should be discussed with committee members before a hearing, so that all members understand why the change was made. If politicians are briefed on why the switch happened, it could prevent accusations during the hearing that the CEO's absence was an evasion rather than a swap.

Questions may arise, even if the CEO's empty chair doesn't come as a surprise—and the present company representative should be prepared to answer them, said Robert Gerchen, a senior consultant at Litigation Insights.

“Say, 'I am the person best equipped to answer the questions that you have on this issue, and here is why,'” Gerchen said.

He agreed that, under most circumstances, companies shouldn't send a CEO to a hearing if he or she isn't the best person to answer committee members' questions. Still, he noted that one exception would be if the company could lose an ally by not sending its requested top executive.

“Send the person who can best tell the story,” Gerchen said.