A federal law clerk in Oregon who was denied healthcare benefits for her same-sex domestic partner was discriminated against and must be compensated, judges have ruled.

The case highlights an apparent gulf between the rights and benefits offered to federal employees who are married and those in domestic partnerships.

Margaret Fonberg, now an attorney in Portland, previously worked as a clerk for US Magistrate Judge Thomas Coffin in the District of Oregon from 2009 to 2013. In 2009 she tried to enrol her domestic partner in her health plan, but the federal Office of Personnel Management (OPM) would not allow it. Ms Fonberg then filed a complaint under the District of Oregon’s Employment Dispute Resolution (EDR) process.

Chief US District Judge Ann Aiken initially ruled that denial of health benefits to Ms Fonberg’s partner was discriminatory and ordered the district to reimburse her for coverage and to award back pay for benefits from January 2010.

However, Judge Aiken rescinded the order in March, stating that because the couple were unmarried, “there was no authority within the Ninth Circuit to permit her to order reimbursement of the cost of health benefits for Fonberg’s domestic partner”.

Oregon does not offer same-sex marriage, but does recognise and provide benefits to same-sex domestic partners.

Yesterday, the Executive Committee of the Ninth Circuit Judicial Council ruled in favour of Margaret Fonberg.

A judicial panel declared that the District of Oregon had discriminated against Ms Fonberg based on her sexual orientation by denying benefits that are available to married opposite-sex couples.

The committee cited this summer’s Supreme Court ruling against the Defence of Marriage Act (DOMA) as highlighting the principle that “federal employees must not be treated unequally in the entitlements and benefits of federal employment based on the vagaries of state law”.

The Ninth Circuit previously issued a similar opinion for Karen Golinski, a California attorney for the Ninth Circuit Court of Appeals who applied for health benefits for her same-sex partner and was denied. Chief Judge Alex Kozinksi, who was also on the panel in Fonberg’s decision, ruled that Golinski was entitled to benefits and could sue OPM. That suit was ultimately dismissed after DOMA was overturned.

In November, a bill banning workplace discrimination against LGBT Americans passed the US Senate.

The Employment Non-Discrimination Act (ENDA) would make it illegal to discriminate against someone on the basis of sexual orientation or gender identity. It is already illegal to discriminate on the basis of race, colour, sex, nationality, religion, age or disability.

However, ENDA is unlikely to proceed further for the time being. Republican US House Speaker John Boehner has vetoed supporting the bill in the Republican-controlled House.