Norton Rose Fulbright's US LLP has rejected claims that it should withdraw from representing client Duke University in a case against the John Wayne Estate after the claimant flagged a conflict of interest between legacy Fulbright & Jaworski and Norton Rose Canada.

The firm's US partnership, which, for regulatory reasons is still legally registered as Fulbright & Jaworski in the US, has been acting for North Carolina's Duke University in a trademarks case against the estate of late Hollywood star John Wayne, which is suing the North Carolina university over the right to market alcoholic drinks branded with Wayne's 'Duke' nickname.

Last month the estate filed a motion with the US district court for the Central District of California to disqualify the US LLP from the case, on the grounds that Norton Rose Fulbright Canada is a longstanding adviser to a minority shareholder of the distillery producing the disputed product.

Fulbright has said that there is no conflict between the two legacy firms, despite their combination under a Swiss verein structure.

In the course of the dispute, the firm said that the June 2013 tie-up has been "mischaracterised" as a merger – a claim that is likely to prompt questions over the level of integration at Norton Rose Fulbright and other Swiss verein firms.

Wayne's estate has questioned Fulbright's assertion that no confidential information could be passed on from the Canadian LLP to the US partnership. In its motion, it said that Norton Rose Fulbright Canada had assisted distillery shareholder Jayson Woodbridge in connection with the dispute, including involvement with developing litigation strategy for both Woodbridge and the distillery.

The motion, which cites press releases issued by Norton Rose Fulbright at the time of the go-live date of the tie-up, said: "The Fulbright firm promised it would provide 'seamless' legal services flowing from each of their member firms to the others.

"In a later release, the managing partner of Norton Rose Fulbright Canada stated, '[…] Our Canadian clients now have new north/south access to the Americas seamlessly with lawyers who are based in each country's key markets'."

It said Fulbright seemed to want "all the benefits of combining its member firms" and to market itself as a legal services "behemoth", but is "unwilling to accept the accompanying burdens of the merger".

However, Fulbright argues that the estate's claim shows a misunderstanding of how Swiss verein arrangements function, pointing out that the firms operate as separate legal entities that do not share confidential information with each other.

Fulbright said in its response: "Importantly, member firms do not share privileged information with other member firms unless they are retained by and working together for a client on the same matter.

"Any other sharing of information is limited to the business of the member firms, [for example] for purposes of checking conflicts or marketing. […] Member firms do not have access to each other's client files."

The filing continued: "In short, while Mr. Woodbridge may be a client of [Norton Rose Fulbright Canada], he is not a client of Fulbright & Jaworski and never has been."

Fulbright has further argued the "appearance of impropriety" is not a separate basis for disqualification. It adds that the estate's case "improperly relies on hearsay 'news accounts' mischaracterising the combination as a 'merger'".

A Norton Rose Fulbright spokesperson said the union between the firms has "always been seen and referred to as a 'combination'", adding that "any misrepresentation has probably been made by the media".

The filing further states that the plaintiff does not have the power to seek disqualification as Woodbridge is a "non-party minority investor in yet another non-party" in the case.

Duke University filed a separate motion to dismiss the case in August. Norton Rose Fulbright litigator John O'Malley and associate Cristina Longoria, both based in LA, are representing Duke University.

John Wayne Enterprises is instructing Californian firm Rutan & Tucker senior partner Richard Howell, partner Ronald Oines, partner David Hochner and associate Jeffrey Fohrer.