On Dec. 14, 2015, an investigator from the Food and Drug Administration (FDA) arrived at Nippon Fine Chemical’s drug manufacturing facility in Hyogo, Japan, to conduct an inspection. But during the inspection, the facility’s quality control manager — in an audacious challenge to the FDA’s legal authority — directed employees to stand “shoulder-to-shoulder” in order to bar the FDA investigator from entering the facility’s quality control laboratory, where drugs destined for the U.S. market were analyzed. A recent FDA warning letter detailed this and other unacceptable behavior by company officials during the agency’s inspection.

Americans depend on medicines produced by foreign drug manufacturers. In fact, the FDA estimates that 40 percent of all finished drug products dispensed in the U.S. and 80 percent of all active pharmaceutical ingredients used in medications consumed by U.S. patients are imported from other countries.

To ensure that drug products flowing into the U.S. from foreign manufacturers are safe and meet the FDA’s rigorous quality standards, inspectors from the agency must have unfettered access to any foreign facility making drug products that are to be imported into the U.S. A key component of an FDA inspection is the assessment of the manufacturer’s quality control laboratories and procedures for testing and analyzing raw materials, intermediate products and final drug products.

As it turns out, the FDA investigator had reason to be concerned about the performance of Nippon’s quality control laboratory at its Hyogo facility. During the inspection, the investigator found records of complaints the company had received from its customers about finding “glass, hair, cardboard, metal, product discoloration, and a black spider” in Nippon’s drugs.

In further attempts to impede the FDA’s inspection, the company refused to provide the agency with copies of these customer complaints, and a quality assurance manager prevented the FDA investigator from taking photographs of equipment used to manufacture drugs distributed in the U.S.

On Aug. 8, 2016 — after several months of reckless hesitation — the FDA finally placed Nippon on an import alert, an action that allows the U.S. to detain all of the company’s drug products at the border. The FDA declared Nippon’s drug products to be “adulterated” because company employees limited the FDA’s inspection of the Hyogo facility, including by refusing to permit the FDA investigator to enter the quality control laboratory.

This is not the first time that the FDA has encountered companies that blocked an agency investigator from inspecting a drug manufacturing facility, and it undoubtedly will not be the last. To protect American patients, the FDA must aggressively inspect drug manufacturers in foreign countries. Moreover, the agency must impose import bans more promptly whenever a company interferes with an FDA inspection, particularly when it finds compelling evidence of poor manufacturing quality, as was the case with Nippon.