The club is challenging a search-and-seizure order obtained by HM Revenue and Customs as part of a National Insurance fraud investigation.
A lawyer acting for the club said the warrants were "excessively wide" and other methods were available for obtaining information.
The hearing at London's High Court is expected to last two days.
In April, St James' Park - along with West Ham United's ground - was raided by HMRC in an investigation into football agents and payments made in transfer dealings between English and French clubs.
Richard Lissack QC, appearing for NUFC, told Lord Justice Beatson and Mrs Justice Whipple: "There were no reasonable grounds for believing Newcastle was engaged in suspected tax fraud."
It was also argued the legal procedures followed when the warrants were obtained at Leeds Crown Court were flawed, and no proper reasons were given.
The hearing continues.
Tax officials "had no reasonable grounds" for believing Newcastle United was engaged in fraud, a court heard.