The court noted that at the time she was accused of killing Ms. Kercher, a Briton, Ms. Knox “had been particularly vulnerable, being a foreign young woman, 20 at the time, not having been in Italy for very long and not being fluent in Italian.” Her statements during the interrogation “had been taken in an atmosphere of intense psychological pressure,” the court said.

The case made headlines for years in Italy, the United States and Britain.

During her interrogation in 2007, Ms. Knox accused her boss, a pub manager, of killing Ms. Kercher, but he was subsequently exonerated. A court later found that she had committed slander, and the European court decision concerned the process leading to that conviction.

On Thursday Ms. Knox, who is 31 now and lives in Seattle, wrote on her blog that she had “spent years wracked with guilt over those statements I signed in the interrogation room.”

Ms. Knox, her boyfriend at the time of the killing, Raffaele Sollecito, and a third man, Rudy Guede, were found guilty of Ms. Kercher’s murder in 2009. But in 2015, Italy’s highest court not only overturned the conviction of Mr. Sollecito and Ms. Knox, who had served four years in prison, it took the rare step of fully exonerating them. Mr. Guede is still serving a 16-year sentence.

In lodging her complaint with the European court, in 2013, Ms. Knox said she had not been assisted by a lawyer during the all-night interrogation, and had not been provided with a professional interpreter. She also claimed to have been subjected to extreme psychological pressure, an allegation the court would determine was unfounded.