has to be done FedEx’s way:

FedEx could cancel contracts for $10 billion in American-made planes if Congress makes it easier for unions to organize the delivery giant’s workers.

In a Securities and Exchange Commission filing, the Memphis-based company disclosed that purchases of Boeing 777s are contingent on FedEx Express’ continued coverage by the National Railway Labor Act.

The disclosure serves as a warning shot to lawmakers seeking to put FedEx Express workers under the National Labor Relations Act, a move seen as helping the International Brotherhood of Teamsters.

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Under the Railway Labor Act, a union like the Teamsters would have to organize FedEx Express employees nationally, rather than in local bargaining units. Drivers for FedEx’s chief domestic competitor, UPS, are largely represented by the Teamsters, but FedEx has fended off organizing attempts for years.