On Aug. 20 and 21, the workers at a Houston plant owned by Lamons Gasket Co. will vote whether to retain United Steelworkers of America as their union. They tried to do this once before, only to have the federal National Labor Relations Board say they were not allowed.

In fact, the workers actually had a vote in 2010, but NLRB impounded the ballots before they could be counted. The board then in 2011 threw out the very NLRB precedent that allowed the workers' vote, a 2007 ruling known as Dana Corp.

What happened at the NLRB had little to do with the particulars of the Lamons Gasket case and much more to do with the board's new Democratic majority under President Obama wanting to reverse something that the previous majority under President George W. Bush had done. The case shows just how important who sits on the NLRB is to how the law is enforced.

That was rotten luck for the Lamons Gasket workers, though, who have had to wait three years for another chance to decertify their union.

The classic Image of union organizing is that of grassroots activism. But many campaigns are actually top-down efforts in which union leaders pressure companies through PR campaigns or other means. This allows union leaders to bypass an NLRB-monitored election since companies can sign contracts on behalf of their workers if they choose.

That's what happened at Dana Corp., a national auto parts maker, in late 2003 when it recognized the United Auto Workers as the union for an Ohio facility. This was after a "Card Check" election, meaning that supposedly most workers signed cards backing UAW. Several employees objected to the deal, however, accusing the company and the union of colluding against them.

Challenges like that ordinarily are barred once the employer and the union reach agreement. But the NLRB ruled in 2007 that there needed to be better balance between promoting stability in union-management relations and protecting workers' right to choose.

The board noted: "Card Checks are less reliable because they lack the secrecy and procedural safeguards of an election."

The solution was to grant employees a 45-day window after a union-management deal to file their own challenge. If 30 percent of workers said they objected, the NLRB would allow a secret-ballot election on retaining the union.

It was not a welcome change as far as union leaders were concerned. They seethed for years and pushed to overturn the ruling.

That happened with Lamons Gasket. The case was similar to Dana: After the company agreed to a Card Check union election, the necessary number of workers petitioned the NLRB for a vote, which an NLRB regional director ordered in 2010.

United Steelworkers appealed this to the board, which by 2011 had a Democrat-appointed majority, including Craig Becker, formerly a top lawyer with Service Employees International Union and AFL-CIO. The board then threw out the Dana precedent altogether.

The new NLRB majority said Dana lacked "any empirical evidence supporting the [previous] majority's suspicion that the showing of majority support that must underlie any voluntary recognition is not freely given or is otherwise invalid." Never mind that actually counting the votes in Lamons Gasket would have provided some evidence either way.

Then-NLRB board member Brian Hayes dissented, noting that there wasn't any evidence that Dana had presented any barrier to voluntary recognition, either: "Our own statistics confirm Dana's benefits and reveal no negatives in the effectuation of statutory goals. Yet the majority concludes that Dana must be overruled."

Should the Lamons Gasket workers decertify their union it will raise serious questions about whether the union ever had the support of a majority of workers in the first place — exactly the sort of situation the Bush-era rule was meant to address. If the vote fails, it will bolster the current majority's move to scrap the rule completely.