What happened

Is labor the Achilles' heel of retail powerhouse Amazon (AMZN 0.11%)? It felt that way on Tuesday, when disquieting news of labor difficulties surfaced. Following that, shares closed the day nearly 2% lower.

So what

This morning, the Retail, Wholesale and Department Store Union (RWDSU) accused Amazon of illegally interfering with a union election in Alabama. The RWDSU did so in formal Unfair Labor Practice charges against the company in a filing with the National Labor Relations Board.

Amazon worker working with a box in a company plant.

Image source: Amazon.

Last year, the RWDSU suffered a defeat in its attempt to unionize the company's center in Bessemer, Alabama. The NLRB tossed that result, however, on the grounds that Amazon illegally influenced the vote (it apparently pushed voters to put their ballots in a receptacle on company grounds). The election is being rerun.

The RWDSU's charges allege a series of suppressive actions by Amazon. Among other examples of misconduct, the monster retailer stands accused of removing union literature from its break rooms, limiting access to such facilities.

Amazon says that it is fully complying with existing labor law. "Our focus remains on working directly with our team to make Amazon a great place to work," Reuters quoted the company as saying in an official statement.

Now what

Allegations of unfair treatment of lower-level Amazon employees is hardly new or surprising. Yet it seems the labor difficulties the company is experiencing aren't being solved; in fact, Amazon appears to be determined to hinder unionization efforts rather than improving its labor relations in certain locales. Investors likely want to see forward movement on this front, as the latest news is troubling.