How a CIETAC tribunal treats your evidence comes down almost entirely to what you did before the dispute started. Not after.

Something I dealt with recently. An American buyer rejected a batch of custom hardware parts, claiming the specs were wrong. He had the contract, had emails, had two months of angry WeChat messages with the supplier. He thought that was enough.

It wasn’t.

The tribunal asked two questions. First: did you inspect the goods within the contractual inspection period (验收期)? Second: do you have a third-party testing report proving non-conformance?

Neither. Zero.

His internal QC team had checked the parts and written up an internal memo. But to the tribunal, that carries about the same weight as telling them “I think my product has a problem.” No independence. Worse, the contract specified a 15-day inspection window after delivery, and his first formal complaint to the supplier came on day 32. Under the logic of Article 621 of the PRC Civil Code, failing to notify within the contractual inspection period can be treated as acceptance of the goods.

The case didn’t end in a total loss. The tribunal weighed other factors. But the damages award came in at roughly a third of what he expected.

How the tribunal looks at evidence

China arbitration’s evidence rules don’t work quite the way many foreign buyers assume. A few structural things are worth explaining upfront.

Burden of proof. The basic principle is “the one who asserts must prove” (谁主张，谁举证). You say the supplier breached. You prove it. Supplier says you didn’t pay on time. Supplier proves it. Sounds obvious, but in practice it means this: even if the respondent doesn’t show up, doesn’t file a defense, doesn’t submit a single document, the claimant still needs to present a complete evidentiary case. No proof, no win.

Standard of proof. For ordinary commercial disputes, the standard is “preponderance of evidence” (优势证据). Your evidence is more persuasive than theirs. That’s the bar. But if you’re alleging fraud, the standard goes up to “clear and convincing.” The difference matters more than people think.

Adverse inference. Article 23 of the 2024 CIETAC Guidelines on Evidence says this: if the tribunal orders a party to produce a specific document and that party refuses without justification, the tribunal may infer that the document’s contents are adverse to them. This principle is common in international arbitration. IBA Rules on Evidence, Article 9.6, has the same provision. But many respondents walk in thinking “you don’t have my documents, so you can’t prove anything.” Under the 2024 rules, that attitude is a liability.

In plain language: if your supplier has factory inspection records but won’t hand them over, the tribunal can treat those records as evidence against the supplier.

Which evidence carries the most weight

At the center of most supply chain quality disputes is one question: were the goods defective or not? Around that question, different types of evidence carry very different weight.

Third-party inspection reports — top tier. Reports from SGS, TÜV, Bureau Veritas, and similar international testing bodies are treated by tribunals as independent technical evidence. Labs accredited under CNAS or CMA carry full legal validity nationwide. Many contracts directly specify that a particular institution’s test results determine whether goods pass or fail.

I’ve said this to clients more times than I can count: your QC manager’s email saying the goods are defective, and an SGS report saying the goods are defective, are completely different things to a tribunal. One is your claim. The other is evidence.

One thing that catches buyers off guard: third-party testing reports formed outside China generally don’t need notarization or consular authentication for submission in Chinese arbitration. After the Hague Apostille Convention took effect in China on November 7, 2023, document authentication got even simpler. Between Convention member states, the old dual-authentication process (20-30 working days) was replaced by Apostille (3-7 working days). And private documents like contracts, correspondence, and testing reports generally no longer require any mandatory authentication at all.

WeChat messages — usable, with conditions. The Supreme People’s Court’s December 2019 amendment to the Rules on Civil Procedure Evidence formally classified WeChat chat records as a type of electronic evidence. CIETAC’s Evidence Guidelines also categorize WeChat records as documentary evidence. But there are hard requirements:

First, identity verification. You need to prove that the person on the other end of the WeChat conversation is actually the contractual counterparty. Not their assistant. Not some contact nicknamed “Zhang Zong” who has nothing to do with the case. Verification methods include: the other party admitting it, linked phone numbers, or in some cases requesting Tencent’s assistance.

Second, completeness. You can’t cherry-pick favorable messages. The records must be reasonably complete, clearly showing the facts you’re trying to prove. I’ve seen clients submit a dozen messages and have the other side say “you cut the context” at the hearing. Tribunals generally don’t accept obviously incomplete records.

Third, corroboration. WeChat records alone typically aren’t enough. They work best when cross-referenced with emails, contracts, payment records, or inspection reports.

One more detail: WeChat voice messages are harder to get admitted than text messages. They’re volatile, hard to identify, and easy to challenge on authenticity. If your supplier denies saying what the voice messages contain, you’ll have a tough time carrying that burden.

Internal QC records — bottom tier. Not inadmissible. You can submit them. But the tribunal won’t treat them as independent evidence. You inspected your own goods. You said they failed. There’s no third-party credibility. In practice, internal QC records function as supporting evidence at best.

A deadline that kills more cases than you’d think

Article 621 of the PRC Civil Code is a provision you may have overlooked, and it has real teeth.

The rule: if the contract doesn’t specify an inspection period, you must notify the seller of quality issues within a “reasonable period.” If you don’t notify within two years of receiving the goods, they are deemed to conform to the contract. Your right to claim is gone.

If the contract does specify an inspection period? You must inspect and raise objections within that period. Miss it, same result.

Article 622 adds a subtle exception: if the contractual inspection period is too short for a thorough examination given the nature of the goods and trade customs, that period only counts as the deadline for objecting to “apparent defects.” Latent defects get a separate reasonable period.

There’s one lifeline: if the seller knew or should have known the goods didn’t conform, the buyer is not bound by the notification deadline. But proving the seller’s knowledge is its own evidentiary challenge.

In the supply chain cases I’ve worked, more claims have been partially or fully dismissed because the buyer missed the inspection window than because of fabricated evidence.

The inspection period isn’t a “best practice” suggestion. It’s a countdown that starts the day goods arrive.

Proving your losses

Suppose you clear the evidence bar. The goods were defective, and you have the reports and records to prove it. Next question: how much did you lose? And how do you prove that?

Article 584 of the Civil Code sets the framework: damages equal the actual loss caused by the breach plus the expected profit from contract performance (可得利益). But damages cannot exceed what the breaching party foresaw or should have foreseen at the time the contract was signed.

You need to prove three things: the loss exists, the amount, and the causal link to the breach.

Actual losses are the easier part. Contract price, cost difference from substitute purchases, shipping, warehousing. Expected profits are harder. If you claim you would have resold the goods to your customer at a 20% margin, you need industry profit rates, historical transaction records, possibly an audit report showing the profit was real and certain.

There’s another rule that gets overlooked: the duty to mitigate (Article 591). As the non-breaching party, you’re obligated to take reasonable steps to prevent losses from growing. If you received defective goods and left them in a warehouse for six months doing nothing, you can’t claim six months of storage fees. You let the loss expand.

The most extreme case I’ve seen: a buyer waited ten months after receiving defective goods before contacting a lawyer. During those ten months, he paid storage costs, missed the window for substitute purchases, and even owed his own client late-delivery penalties. The total of those secondary losses exceeded the value of the goods themselves. The tribunal only awarded a portion, because reasonable mitigation would have meant arranging a return or replacement purchase much sooner.

Evidence preservation

If you’re worried the supplier might destroy evidence, say deleting factory QC logs or scrapping defective samples, you can apply for evidence preservation (证据保全).

During arbitration, you submit the application to the arbitration commission, which forwards it to the relevant court. For domestic cases, the court with jurisdiction is the basic people’s court where the evidence is located. For foreign-related cases, it’s the intermediate people’s court. The arbitration commission doesn’t review the application itself. It just passes it along.

You can also apply before arbitration begins. In urgent cases, the court must rule within 48 hours.

The court may require you to post security. And if the other side destroys or moves evidence that’s already under a preservation order, the court can presume your claims about that evidence are true. That’s essentially a form of adverse inference.

Electronic evidence preservation is increasingly important. Options include notarization (a notary witnesses the collection process and issues a notarial certificate) and third-party blockchain platforms. The Hangzhou Internet Court affirmed the admissibility of blockchain evidence back in 2018. SHA-256 hashing combined with metadata timestamps, recorded on-chain, makes tampering detectable. It’s cheap, fast, and particularly useful for preserving webpage content or chat records.

A checklist for you

If you’re doing goods trade with Chinese suppliers, whether or not there’s a dispute on the horizon, here’s what you should be doing continuously:

  • Complete inspections within the contractual inspection period (or immediately upon receiving a claim), and document the inspection date and results in writing
  • When you find a quality issue, notify the supplier in writing within the contractual or reasonable period — email, formal letter, or at minimum a WeChat message followed up by email
  • Arrange third-party testing — SGS, TÜV, Bureau Veritas, or any CNAS/CMA-accredited lab
  • Keep defective product samples — physical evidence in a quality dispute can be more powerful than any document
  • Don’t delete WeChat conversations, and don’t submit only excerpts — get them notarized if possible
  • If you suspect the supplier might destroy evidence, talk to a lawyer about an evidence preservation application immediately
  • Prepare Chinese translations for all non-Chinese evidence

This isn’t a checklist for after a dispute breaks out. It’s one you should be referring to from the moment you sign the contract and receive the first shipment.

If you’re sitting on a supply chain dispute and aren’t sure whether your evidence is sufficient, what’s missing, or whether there’s still time to fill the gaps, reach out to me directly. I can do an evidence audit and tell you where you stand.

This article is the fifth in the “China Supply Chain Disputes — What Every Buyer Should Know” series. Previous: Arbitration in China Is Less Scary Than You Think (and Probably Cheaper Too). Next: Your Supplier Copied Your Design and Is Selling It to Your Competitor.