Paper Trails and Port Records: How US Importers Are Winning Demurrage Disputes Through Public Data

For most US importers, a demurrage invoice arrives and gets paid. The amounts are frustrating, the timelines feel arbitrary, and the process of disputing a charge seems more trouble than it is worth. That calculation, however, is changing. Armed with publicly available port authority data, Freedom of Information Act (FOIA) requests, and a clearer understanding of what carriers are — and are not — legally permitted to bill, importers are increasingly finding that the evidence to challenge erroneous charges has been sitting in government databases all along.

This is not a niche legal strategy reserved for large multinational shippers. It is a practical compliance tool available to any importer willing to invest the time to understand how demurrage billing is supposed to work — and where it routinely does not.

Understanding What Demurrage Is Actually Supposed to Measure

Before an audit can begin, importers need a precise understanding of the charge itself. Demurrage is assessed when a container remains within a terminal beyond the carrier's free time allowance. It is intended to compensate terminal operators and carriers for the cost of occupying yard space that could otherwise be used for incoming cargo.

The Federal Maritime Commission (FMC) has been explicit, particularly in its 2020 interpretive rule and subsequent guidance, that demurrage charges must serve an incentivizing function — meaning they should only apply when the importer had a genuine, practical opportunity to retrieve the container and failed to do so. When port congestion, equipment shortages, terminal gate closures, or carrier-side delays prevent pickup, the legal and regulatory basis for the charge weakens considerably.

This is the foundation of every successful demurrage dispute: demonstrating that the charge was assessed during a period when retrieval was not reasonably possible.

Step One: Obtain the Carrier's Billing Record and Free Time Schedule

The audit process begins with the carrier's own documentation. Request a complete billing record that identifies the specific container number, the date free time commenced, the daily rate applied, and the total days billed. Cross-reference this against the carrier's published tariff, which must be filed with the FMC and made publicly accessible through the agency's tariff search system.

Discrepancies between the published tariff rate and the invoiced rate are among the most common billing errors found during audits. Carriers occasionally apply surcharges or escalating rate tiers that were never properly filed, or they bill at rates that have since been updated without adequate notice to the shipper.

Step Two: Pull Terminal Dwell Time and Gate Activity Records

This is where public data becomes a powerful tool. Most major US port authorities — including those overseeing the Port of Los Angeles, the Port of Long Beach, the Port of New York and New Jersey, and the Port of Savannah — publish operational performance metrics on a regular basis. These reports frequently include average container dwell times, gate turn times, vessel arrival and departure data, and periods of declared congestion or operational disruption.

Importers can access these records directly from port authority websites, often without any formal request. When published dwell data shows that average container retrieval times during the billing period were significantly elevated due to systemic terminal issues, that data constitutes documentary evidence that the importer's delay was not attributable to their own inaction.

For more granular records — including specific gate transaction logs, appointment system data, or internal operational communications — a FOIA request to the relevant port authority or to a federal agency such as US Customs and Border Protection may yield additional supporting documentation. FOIA requests submitted to CBP can surface exam holds, inspection delays, and processing backlogs that directly affected a container's availability status.

Step Three: Document Every Touchpoint on Your Side

Public records establish the external environment. Internal records establish your conduct within it. Every importer undergoing a demurrage audit should compile a complete timeline of their own actions: when the arrival notice was received, when the customs entry was filed, when the customs release was issued, when a dray appointment was requested, and when the terminal confirmed or denied availability.

If your customs broker submitted the entry on time and CBP processing delays extended the hold, that sequence is documented in the entry filing system. If the terminal's appointment portal showed no available slots during the free time window, screenshots and system-generated confirmation emails are admissible evidence in a formal dispute.

The goal is to construct a day-by-day account that maps your actions against the external constraints documented in port authority and federal records.

Step Four: Identify the Specific Regulatory Violations

Once the timeline is assembled, the audit shifts to a regulatory analysis. The FMC's demurrage and detention guidance provides several grounds on which a charge may be challenged:

• Billing during periods when the container was not actually available for pickup — including holds placed by CBP or other government agencies, or periods when the terminal had suspended gate operations.
• Application of charges that were not properly disclosed in the carrier's tariff — including fees added after the booking was confirmed or rates that were not filed with the FMC at the time of billing.
• Double-charging, in which both the ocean carrier and the terminal operator assess demurrage for the same dwell period without clear contractual basis.
• Failure to provide adequate notice, particularly when the carrier did not issue a timely arrival notice or did not communicate changes to free time commencement dates.

Each of these grounds corresponds to a specific regulatory standard. Citing the applicable FMC rule or guidance document when submitting a dispute elevates the claim from a general complaint to a compliance-based challenge — one that carriers are obligated to address under their own tariff dispute resolution procedures.

Step Five: Submit the Dispute Through the Right Channels

Most carriers maintain a formal dispute resolution process for demurrage and detention claims. Submit the dispute in writing, attach the full audit package — billing records, tariff comparisons, port authority performance data, FOIA-obtained documents, internal timeline, and the specific regulatory provisions at issue — and request a written response within a defined timeframe.

If the carrier fails to respond or declines the dispute without substantive explanation, the FMC's Bureau of Enforcement accepts informal complaints and, for larger disputes, formal complaint filings. The FMC has demonstrated increasing willingness in recent years to investigate systemic billing practices, and a well-documented individual complaint can contribute to broader enforcement action.

The Broader Lesson: Compliance Is a Two-Way Obligation

Demurrage disputes are frequently framed as importers seeking to avoid legitimate charges. The more accurate framing is that carriers and terminal operators bear compliance obligations that are often unmet — and that the regulatory framework exists precisely to protect importers from charges that do not reflect actual commercial reality.

The public records infrastructure at US ports is more robust than most importers realize. Port authorities publish performance data to promote transparency and accountability. Federal agencies maintain records that document government-caused delays. FOIA statutes exist to make those records accessible.

Using that infrastructure to audit a demurrage invoice is not an adversarial act. It is the exercise of rights that the regulatory system was designed to provide. For importers willing to build the audit habit, the returns — in refunds recovered, future charges avoided, and leverage gained in carrier negotiations — are substantial.