The policy issues raised in the Justice Department's dispute with Apple Inc. over a locked iPhone represent the "hardest question I've seen in government," FBI Director James Comey said Thursday.

"It's really about who do we want to be as a country and how do we want to govern ourselves," Comey told the House Intelligence Committee.

A week ago, a federal magistrate in California directed Apple to help the FBI hack into a phone used by one of the assailants in the December mass shooting in San Bernardino, California.

Apple was expected to file a formal objection on Friday.

Comey reaffirmed what he posted in a blog Sunday night: that the Justice Department was not trying to set a precedent by going to court to obtain access to the phone.

Instead, he said, "It's about trying to be competent in trying to investigate something that is an active investigation."

Apple's chief executive, Tim Cook, told ABC News that it would be "bad for America" if his company complied with the FBI's demand and that he was prepared to take the fight to the Supreme Court.

Comey said Apple had been "very cooperative" in the months leading up to the court fight and that there have been "plenty" of negotiations between the two sides. But at some point, Apple reached a point where it was not willing to do what FBI was asking.

Comey acknowledged that last week's order could help guide other courts considering the same issue in the future. But he rejected Apple's assertion that the order could create a slippery slope affecting millions of other iPhone users.

Comey insisted that the code the FBI was asking Apple to create would work only on that one phone and would be retained by Apple.

Apple has argued that doing so would make other iPhones more susceptible to hacking by authorities or criminals in the future.