The US Federal Maritime Commission is looking into how the top 20 container shipping companies calling on the US are complying with new rules against retaliation against shippers passed earlier this year.

The commission said its vessel operating common carrier (VOCC) audit team began its investigation earlier this week by sending correspondence to each of the companies with an aim to find out how they are training employees on the new rules and how aware those employees are of the potential punishments.

“The FMC will thoroughly investigate any allegation of illegal behaviour and prosecute aggressively when warranted,” chairman Daniel Maffei said.

“This is something that everyone in a company, from the newest sales associate to the CEO, must understand and that is why the VOCC audit tam is carrying this message directly to ocean carriers serving the United States. Even a simple verbal threat to a shipper from an ocean carrier employee could undermine US law and will not be tolerated.”

The new rules were laid out in the Ocean Shipping Reform Act, signed into law in June.

The law was passed after President Joe Biden launched a push to examine competitiveness in the container shipping industry in the summer of 2021 amid record port congestion and accusations liner operators were hurting US exporters.

The legislation received the scorn of the World Shipping Council, which argued that problems with the supply chain were not the fault of liner operators but of issues on shore.

Biden’s push was followed by a litany of US companies filing legal complaints with the FMC, many alleging broken contracts and wrongly issued detention and demurrage charges.

The highest-profile complaint was filed by Samsung Electronics America, the US subsidiary of South Korean electronics giant Samsung Electronics, which accuses Zim of retaliating against it once it began complaining about unclear and repeat charges.

The VOCC audit team was established in June 2021 to assess liner operators’ compliance with FMC rules around detention and demurrage charges. The team was also ordered to investigate how well liner operators serve US exporters.

The FMC did not respond to a request for it to identify the 20 companies involved.

The VOCC audit team had previously identified AP Moller-Maersk, Mediterranean Shipping Co, CMA CGM, Cosco Shipping Lines, Hapag-Lloyd, Ocean Network Express, Evergreen Line, HMM and Yang Ming Marine Transport as the nine largest liner operators.