In the ongoing legal battle between Apple and Samsung, it's emerged that due to a clerical error, one of Samsung's lawyers is not allowed to practise law in the court - a paperwork mixup that could lead to penalties for the Korean electronics giant.

Samsung could face penalties from the US District Court in Northern California after one of its lawyers involved in the Apple v Samsung patent battle against Apple admitted that she hadn't filed the paperwork necessary to practise law in front of the court.

Susan Estrich, a high-profile lawyer and law professor at the University of Southern California law school and a legal contributor to Fox News, made the admission in a filing on Thursday to the court's San Jose division.

Estrich is a partner at Quinn Emanuel Urquhart & Sullivan, the law firm working for Samsung in the case, and she appeared in front of the court two days earlier to argue about email that could be used as evidence in the case.

Apple Samsung court cased

On Wednesday, Magistrate Judge Paul Grewal questioned whether the relevant paperwork had been submitted for her appearance.

"In reviewing the docket, it appears that the Samsung attorney presenting Samsung’s argument has not entered any appearance in this case," Grewal wrote. "Ordinarily under these circumstances, the court would simply remind all counsel of this obligation and request that this error be corrected without undue delay. The presiding judge has made clear, however, her expectation that such appearances precede any presentation in this court, and that all counsel be admitted to practise in this court.

"Upon further review the court has discovered that not only did counsel present arguments without first entering an appearance, there is no record in the court’s database that she is admitted to practise in this court. This is potentially a more serious breach. While the requirements for admission to this district’s bar may not be particularly onerous for one licensed to practice law in the State of California, they are no mere formality."

At the time, Grewal acknowledged it could have been a clerical error at the courthouse and asked Estrich to confirm whether she had been admitted to practise before the court.

On Thursday, she filed papers requesting admittance and moments later submitted an explanation for the error that began with a belief that she had been admitted to the Northern District court.

"The basis of my belief was that when I moved to California in 1986 I joined a law firm and believed that the law firm facilitated and assisted me in complying with the administrative requirements for my admission to the District Courts in the state. In addition to the Central District of California, I am admitted to practise before the United States Court of Appeals for the Ninth Circuit, and the United States Supreme Court," the explanation read.

"That law firm has since dissolved. As a result of these circumstances, I did not confirm my membership to practise before this Court. My omission was through inadvertence and oversight, and my conduct was not willful."

In his notice on Wednesday, Grewal held out the possibility of penalties but didn't specify what they might be.

Samsung has already faced at least one penalty for legal errors.

The case revolves around a basic allegation that Samsung copied Apple's iPhone and iPad designs in its own products. Samsung had hoped to argue that Apple came up with those designs based on influences from other companies, including Sony. But it was stopped from presenting several "Sony-style" mock designs because that evidence wasn't brought up fast enough during the preparatory phase for the current jury trial.

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