The United Synagogue is being sued for religious discrimination by a former kosher supervisor who, apparently, is claiming there were objections to his beard.
Jonathan Abrahams, 58, who lives in Stamford Hill, north London, was made redundant as a full-time shomer with the organisation's kashrut division over a year ago.
But after unsuccessfully applying for other positions within the US, he has filed claims of age and religious discrimination against it.
The JC understands that Mr Abrahams, who is a Lubavitcher, is arguing that his beard was regarded by US officials as too unkempt.
The US said it would vigorously contest the claims, which are due to be heard in a tribunal in Watford next month.
Meanwhile, a spokesman for the Chief Rabbi said that Lord Sacks was "extremely disappointed" that disputes involving rabbis have ended up in court.
Last week Rabbi Mendel Lew, senior rabbi of the largest US congregation, Stanmore and Canons Park, obtained an interim injunction from the High Court to stop disciplinary action against him by the United Synagogue.
The US is also facing a claim of unfair dismissal from Rabbi Ariel Abel, who left Radlett Synagogue last summer.
Lord Sacks's spokesman said it was inappropriate to comment on the two cases as they were before the courts.
But the Chief Rabbi was "always ready to mediate disputes, especially those concerning the relationship between a rabbi and his congregation", his office said.
The Chief Rabbi "maintains that an attempt should always be made to resolve matters internal to the community within the community, by mediation or through the Beth Din".