Defamation case: False smoke alarm rating leads to legal battle

Court rules 'poor' smoke alarm rating was unlawful and defamatory

Press Release No. 23/2026

Publishing a product rating of "poor" in a comparative product test constitutes an unlawful interference with an established business operation if the test was not conducted properly, the Higher Regional Court of Frankfurt am Main (OLG) ruled today. If the publisher commissions a specialized and accredited testing institute to carry out the product test, it may still be liable for damages—particularly if the manufacturer points to specific indications that the test results are incorrect and the publisher fails to adequately investigate these concerns before publication.

The plaintiff manufactures, among other products, smoke alarms. The defendant publishes comparative product tests with ratings. It had tasked an external testing institute with conducting functional tests on the smoke alarms in question—tests that are highly standardized and governed by DIN EN regulations. Three out of four of the plaintiff's products failed to trigger an alarm within the required parameters during the test fires. However, the test fire had fallen below the lower threshold specified in DIN EN 14604:2005. Contrary to the prescribed test protocol—and unbeknownst to the defendant at the time—the testing institute, following an internal directive, deemed the test fire valid and did not repeat the test. The defendant then sent the results to the plaintiff, who raised objections, submitted conflicting test reports from other certified and accredited institutes, emphasized that all its products complied with EN standards, and demanded that the defendant refrain from publishing the test results.

Nevertheless, the defendant proceeded to publish an article on the tested smoke alarms, including a tabular evaluation in which the plaintiff's product received a "poor" quality rating. During the legal proceedings, the defendant—without admitting any legal obligation—permanently acknowledged the plaintiff's injunction claim and later reported in its magazine that it was withdrawing the disputed rating.

The parties remain in dispute over a claim for €7.7 million in damages. The Regional Court, advised by experts, ruled in favor of the plaintiff's claim for damages in principle.

On appeal, the 16th Civil Senate (Press Senate) of the OLG upheld the decision, confirming that the plaintiff is entitled to damages due to the unlawful interference with its established business operations resulting from the "poor" rating. The court found that the rating was capable of harming the plaintiff's reputation and undermining confidence in its products. The interference was unlawful because the testing institute's procedures—which formed the basis of the report—were not conducted with due expertise. The test result was unreasonable, as the test fire had fallen below the prescribed threshold. According to the test protocol and DIN EN standards, the fire should not have been deemed valid—contrary to the institute's handling of the case.

The court ruled that the defendant was liable for this unlawful interference with the plaintiff's business operations. Given the concerns raised by the plaintiff, the defendant should have had "substantial grounds" that "ought to have raised doubts about the proper execution of the smoke detector test." The divergent test results from the institutes commissioned by the plaintiff "should have prompted further scrutiny." When another equally reliable and accredited testing body reaches a different conclusion, the defendant was at least obligated to ask the institute it had hired how such discrepancies arose. Had the defendant done so, it would likely have discovered that its contracted institute—contrary to the test program requirements and DIN EN standards—was internally classifying test fires as valid even when they fell below the threshold curve.

Though the question ultimately did not need to be decided, the senate emphasized that it does not consider it appropriate to extend so-called strict liability without fault to external companies hired by a party—as the lower court had done in this individual case.

The ruling is not yet final. The defendant may still file a non-admission complaint to seek leave for an appeal.

Higher Regional Court of Frankfurt am Main, Judgment of April 23, 2026, Case No. 16 U 38/25(preceded by Frankfurt Regional Court, Judgment of April 3, 2025, Case No. 2-03 O 430/21)

The decision will be available shortly at www.rv.hessenrecht.hessen.de.