What's bad about a union? Avoiding an ideological position to focus on the practical consequences of unionization, Cassidy noted that an employer "loses control over the terms and conditions of employment," ceding that control to a union. So you get no credit for granting raises or enhancing benefits. If workers strike, you can't fire them, and if any of your key suppliers are unionized, their workers will honor picket lines at your facilities, which could cripple your operations. Worst of all, top management is likely to blame HR for the union's intervention in the company.

So how can you prevent it? Simply put, Cassidy says, "Do the right thing" for your workers. "Most employees see a union as a savior that will ensure they're treated fairly. Treat them fairly, and they won't want to pay union dues to gain what they already have." In this realm, thorough training of first-line supervisors is crucial.

What if they get a foot in the door? Most of your employees may be satisfied with their jobs and benefits, but a few disgruntled workers can help a union gain entrance. So HR must continually monitor the workplace for signs of union infiltration. Here's what to look for: (a) more informal employee gatherings, especially huddling in corners or bringing together people who haven't been friends; (b) a sharp rise or drop in employee complaints, or more complaints being lodged by groups rather than individuals; (c) such union buzzwords as "concerted activity," "economic pressure," "job security," "duty to bargain," or "right to representation"; (d) former employees, especially those you've fired, hanging out in the parking lot; and (e) leaflets or handbills left in break rooms or parking lots.

If you see one or more such signs, kick into action: Communicate about how competitive your wages and benefits are; use comparisons with other firms in your industry. Tell employees that no union can prevent either layoffs or higher healthcare premiums. If you must take either or both such actions, explain early and fully why you must. Emphasize managers' open-door policies.

Tip: TIPS is the acronym for what you cannot do once a union has filed a petition. You must avoid threats, investigations, promises, or surveillance. On average, you will have 42 days before the election to conduct a pro-management, not antiunion, campaign.