WASHINGTON — In July 2014, after Jonathan J. Pollard had served 29 years of a life sentence for spying on behalf of Israel, his hopes for freedom were thwarted when a federal panel denied his request for parole.

But that hearing set in motion an intense scramble by lawyers for Mr. Pollard to ensure a different result a year later, when he would be eligible for parole after serving 30 years. They wrote letters, cited statistics and introduced evidence that their client met two legal standards for parole: that he had behaved well in prison, and that he posed no threat of returning to a life of espionage.

On Tuesday, the effort finally succeeded, as the United States Parole Commission announced that Mr. Pollard, 60, met the legal standards and would be released just before Thanksgiving.

Mr. Pollard, one of the country’s most notorious spies, will walk out of federal prison in Butner, N.C., on Nov. 20. Eliot Lauer, one of the two lawyers who have been working pro bono for the past 15 years to free Mr. Pollard, called his client on Tuesday with the news.