The daughter of Robert F. Kennedy has won a federal legal battle to claim a six-foot-high urn planter from the front yard of “Hickory Hill,” the family’s former home in McLean, Va., after a judge ruled that an agreement made in 2010 by the estate’s new owner to relinquish it was binding, even though he made it under the mistaken belief that the urn was a family heirloom.

Lawyer Kerry Kennedy, the seventh of Robert and Ethel Kennedy’s 11 children, grew up at Hickory Hill, which her family moved into in 1957. In December 2009, Ethel Kennedy sold the property, with a pool, tennis court and nine-bedroom, 11-bathroom house to communications executive Alan J. Dabbiere for $8.25 million, real estate records show. Dabbiere agreed to lease back the property to Ethel Kennedy through May 2010, as home buyers often do to allow the residents time to pack up.

So in the spring of 2010, court records show, Ethel Kennedy wrote a memo to her nine surviving children, saying “There are a number of items of personal property that I would like to give you.” She provided a list of the items, prepared by Sotheby’s, and a “draft order” of selection for the siblings, by order of birth, court records show. Each Kennedy sibling could pick three items in a “snake draft” with the ninth child also picking tenth, the eighth child picking next, and so on.

Kerry Kennedy chose the urn planter in the front yard, which she said she treasured because it was just outside her bedroom window and was one of the few things the family owned that had belonged to her uncle, President John F. Kennedy, her grandfather Joseph P. Kennedy, and to the previous owner, Supreme Court Justice Robert H. Jackson. When Jackson died in 1954, his executors sold the estate to then-Sen. John F. Kennedy, who swapped residences with his brother Robert in 1957, while deeding it to their father until 1965.

After Ethel Kennedy moved out in May 2010, Kerry Kennedy tried to make arrangements to pick up the urn. But Dabbiere resisted. He felt the urn conveyed with the property as a fixture. The two sides emailed back and forth.

At the time, Kerry Kennedy mistakenly believed that the urn had been brought to Hickory Hill by Jackie Kennedy, from her own family’s estate, in the 1950s. So Dabbiere agreed to a compromise: He would keep the urn for 10 years, and then relinquish it to Kennedy.

In an email written in June 2010, Dabbiere wrote: “Kerry, the purpose of this email is to memorize [sic] our conversation that the Urn in the front of Hickory Hill will remain as your property and we give up any rights to it conveying with the property and in exchange you agree that the Urn will stay in its current place for 10 years from today’s date — June 16th, 2010. At that time, you are free to take the urn. I will sign a copy of this email and send you a signed PDF version via email.”

But in the course of renovating and researching Hickory Hill, Dabbiere found that Jackie Kennedy had not brought the urn there. It had been there when Jackson purchased the house in 1941. When Kerry Kennedy began asking about retrieving it early, in 2018, Dabbiere resisted.

“The history was the key reason I agreed to convey the urn back to her,” Dabbiere told The Post last year, “after I believed it had conveyed to me with the property.” Dabbiere, 59, is the chairman of OneTrust, which manages privacy and security for the computers and mobile devices of government agencies and private organizations. At that time, he said the urn should stay at Hickory Hill. “I believe this is a mutual mistake of fact and consequently the email agreement to convey the urn back to Kerry is in question. I believe this is a situation where the courts can and will decide fairly based on the facts.”

Kennedy filed suit last July, and after both sides briefed and argued the case, U.S. District Judge Anthony J. Trenga granted summary judgment for Kennedy on June 23. He ruled that the 2010 email was “a valid enforceable agreement,” and that the urn was personal property, not a fixture of Hickory Hill, in part because it wasn’t physically attached to the property and had been moved from time to time.

Trenga said that Kerry Kennedy didn’t know in 2010 that the urn wasn’t brought to the property by her Aunt Jackie, so she hadn’t intentionally defrauded Dabbiere. And the judge found that Dabbiere had learned of the urn’s true origins in 2015, but hadn’t raised that with Kennedy until 2020, so he couldn’t rescind the contract “based on mutual mistake or fraud” because Virginia has a two-year statute of limitations.

And the contract itself made no mention of the urn’s origins. “The alleged mutual mistake,” Trenga wrote, “had nothing to do with the substance of the contractual bargain and did not affect the performance of that contract.” Dabbiere had the urn for 10 years and received his end of the contract, the judge ruled. Now it is time for Kennedy to receive her end of the contract.

Kennedy said that “the dispute regarding the urn has been resolved to our satisfaction and the urn is in the process of being returned to me.” She said it would be placed at her home near the famed Kennedy compound in Hyannis Port, Mass., next month.

Dabbiere said in an email the case was “being resolved to everyone’s satisfaction.”