A federal judge in Manhattan declined on Tuesday to suppress statements made to the authorities by a son-in-law of Osama bin Laden who is charged with conspiring to kill Americans.

Lawyers for the defendant, Sulaiman Abu Ghaith, had argued that he was not adequately advised of his rights and did not voluntarily waive them during an F.B.I. interrogation as he was being flown to New York from Jordan. They said his statements had been the product of “implied threats, humiliation, sleep deprivation” and other forms of coercion.

But Judge Lewis A. Kaplan of Federal District Court found Mr. Abu Ghaith had been advised of his rights before the “vast bulk of the questioning began.” Before the warnings were read, the judge said, Mr. Abu Ghaith was asked questions under the so-called public safety exception to Miranda rights. Immediately thereafter, he was advised of his rights and “replied that he understood them.”

The judge said evidence presented during a suppression hearing “contradicts starkly” Mr. Abu Ghaith’s claim of harsh treatment, and that his statements were voluntary.