"There's usually a higher incident rate and more of a safety concern in the manufacturing industry," Sellers says. "Workers' comp premiums are always in people's minds in keeping the employees safe, and that's why more manufacturing companies do drug testing. They want to make sure they don't have anyone impaired working on machines that could endanger other people."

The legalities behind pre-employment screening

During the pre-employment screening process, there are certain legal issues that HR professionals should consider, especially surrounding the Americans with Disabilities Act and the Americans with Disabilities Act Amendments Act. For some manual labor jobs, a physical may be necessary to ensure the job candidate can successfully perform the "essential job functions," but if he or she does not pass the physical, special accommodations to help that person in the job must be considered.

"We need to consider whether they can do it if we provide them some sort of accommodations," Sellers says. "We can get in a lot of trouble if we don't hire someone because they didn't pass their physical when we didn't take the accommodation into consideration."

Social media is a particularly hot legal topic in pre-employment screening, Sellers says, and there are two perspectives on the issue. One school of thought believes an employer should look at a prospective employee's social media presence, such as a Facebook page, because it gives the employer a chance to see if that individual participates in unbecoming activities or behaviors.

For instance, by viewing a Facebook page, an employer can see a perspective employee's marital status, religion and political affiliation – all of which should not be considered during the hiring process.

"Those are issues that we really should not know or take into consideration when we're trying to hire someone for their qualifications," Sellers says. "It's dangerous to have access to that information, so that's why some attorneys say don't even go there."

In fact, a recent study by the Society of Human Resource Management shows that only 18 percent of employers rely on social media for pre-employment screening, despite the common belief that it is widely used. Of the surveyed employers, 66 percent say they do not use social media as a pre-employment screening tool because of legal issues.

For an employer that is set on using social media during the pre-employment screening process, Sellers suggests hiring a third-party company to handle that task, which could save the employer from potential liabilities.

"If a company really wants the Facebook records checked, it would be better off hiring a third-party reference-checking company and telling it what to looking for," Sellers says. "Then, the company would have that third party look at a potential employee's Facebook page and submit a report to the company. That way the company never had access to that info page."