And at a recent dinner party, Mr. Epstein recalled, he joked about what might happen if his irrepressible and indefatigable wife were sentenced to home detention. "It wouldn't be very good from my point of view," Mr. Epstein said with a laugh.

But yesterday, as Ms. Miller was sent to the federal Alexandria Detention Center in Virginia for four months, a more somber reality emerged. Just before marshals ushered her out of the courtroom, she turned to Floyd Abrams, one of her lawyers, and said she knew she was doing the right thing. "She was sure in the end she was keeping faith with her promise," Mr. Abrams said.