Tobacco use (particularly pertaining to secondhand smoke) in the workplace has been a topic of discussion among human resource professionals for decades. Many businesses, buildings and even entire states have banned indoor smoking, which clarified the issue for a while – until new technologies began muddying the waters once more.

Electronic cigarettes, or e-cigarettes, which vaporize nicotine, are an emerging industry (to the tune of some $200 million in national sales), and as some workers transition from traditional cigarettes to the electronic ones, the workplace can become a free-for-all.

"I don't think it's clear at all that existing tobacco policies also cover the use of e-cigarettes," says Darin Mackender, an employment-law partner at Fisher & Phillips. "Companies need to consider whether their policies cover e-cigarettes or whether they need to clarify those policies or implement new policies. And they shouldn't assume that an existing policy covers e-cigarettes."