A New York premarital agreement signed by an heir to the Hermes fortune is valid, even though a subsequent French agreement the couple signed may have failed to include exclusions anticipated by the initial agreement, a Manhattan judge has held.

Mathias Guerrand-Hermes argued that the court should throw out the New York prenuptial on the grounds of “mutual mistake.” Both parties believed the French agreement, which they signed two days later, would include substantial waivers of property rights by the wife. The French waivers, it turns out, may not have been as strong as one or both parties originally believed.

Manhattan Supreme Court Justice Harold Beeler rejected Mr. Guerrand-Hermes’ motion on several grounds, including that any potential mistake occurred after the first agreement was ratified, and therefore had no bearing on its validity.

“[T]he alleged ‘mistake’ did not exist at the time of the signing,” Beeler wrote in Guerrand-Hermes v. Guerrand-Hermes, 350263/06. “If a lack of waivers under the French Agreement could conceivably constitute a mistake, then that mistake occurred after entering into the New York agreement that husband seeks to invalidate.”

Mathias and Valesca Guerrand-Hermes signed one premarital agreement in New York on May 10, 1999, and a second one in France on May 12, 1999. The same day they signed the French agreement, they married.

On May 5, 2006, Ms. Guerrand-Hermes, a former model, served her husband, an executive for his family’s businesses, with an action for divorce.

In the present motion for partial summary judgment, she sought to enforce the New York prenuptial agreement.

Under the terms of the New York agreement, “after the marriage” Ms. Guerrand-Hermes would receive the rights to two U.S. properties — a Manhattan apartment and a Warren, Conn., house — without any new encumbrances.

In exchange, she would sign a French agreement — the one she signed two days later — in which she would waive “any rights to any interest” in the Hermes family business.

Mr. Guerrand-Hermes opposed his wife’s present motion for summary judgment on several bases. He argued that the two agreements needed to be read together — or, as his attorney told Beeler during a hearing, the court needed to look at the “eight corners” of the agreement.

Mr. Guerrand-Hermes also contended the New York agreement was void under the doctrine of mutual mistake.

“Under husband’s theory,” Beeler wrote, “were this court, in interpreting the French Agreement, to later find that wife did not waive her rights to husband’s property to the extent originally anticipated by the New York agreement, then the parties signed the New York Agreement under a mutual mistake of fact.”

ISSUE OF NEGOTIATION

The chief sticking point, it seems, is whether the wife’s waiver of “any rights to any interest” in the Hermes family business extends to two 2 percent interests in property concerns Ms. Guerrand-Hermes received from her father-in-law.

In a recent decision, Beeler granted Ms. Guerrand-Hermes’ motion for summary judgment.

Not only did the allegedly mistaken waivers in the French agreement postdate the contested New York agreement, Beeler wrote, any “mistake” would be merely unilateral, and therefore not invalidating.

“[T]o the extent husband believes that the waivers may be inadequate, that would be due to his own negligence in negotiating,” Beeler wrote. “Husband is a sophisticated party, who was represented by counsel of his own selection. If a mistake exists, it is merely unilateral, and it will not justify recession.”

Anthony P. Daniele represented Ms. Guerrand-Hermes. Daniele called the judge’s willingness to decide the issue on summary judgment the most unique aspect of the decision.

“In a matrimonial case where they’re contesting the prenup, you just don’t see summary judgments,” Daniele said.

Robert S. Michaels represented Mr. Guerrand-Hermes. Michaels said his client is considering filing a motion to renew and reargue.

If and when the case goes to trial, it will be before a new judge, the third one assigned this year.

After Beeler was reassigned to the Transit and City Transit part in January, the case was transferred to Justice Rosalyn H. Richter, who was appointed last week to the Appellate Division, 1st Department, bench.

Bronx Supreme Court Justice Ellen Gesmer will be taking over Richter’s case inventory, according to an Office of Court Administration spokeswoman.

Mr. Guerrand-Hermes recently made headlines for attacking a pilot who attempted to calm him down on an Air France flight from Paris to John F. Kennedy International Airport. According to a federal complaint filed in Brooklyn, Mr. Guerrand-Hermes tried to punch the pilot, and then “grabbed the Captain’s genital area.”