The US Supreme Court will make a rare foray into popular clothing Wednesday to weigh in on accusations that Abercrombie & Fitch illegally rejected a Muslim job applicant because of her hijab.

Abercrombie argued that its store policy forbids sales staff -- whom it calls "models" -- from wearing "caps" of any sort, and that Samantha Elauf, then 17, should have made clear in her 2008 interview that she could not comply due to her religion.

"Before her interview, Ms Elauf knew the position required her to model the Abercrombie style, knew the style of clothing that Abercrombie sold and also knew that Abercrombie did not sell headscarves," the company said in a court brief.

It stressed that floor staff are expected to sport a "classic East Coast collegiate style."

The Equal Employment Opportunity Commission (EEOC) filed a complaint on behalf of Elauf against Abercrombie & Fitch, which is known for sales associates often dressed in racy attire, and attorneys say she is protected by the 1964 Civil Rights Act.

Under the act, no one can be refused employment based on their religion, unless the employer cannot accommodate the person's religious beliefs without adversely affecting business.

The closely watched case could have deep ramifications for how businesses hire their employees because it would place the burden on employers to warn job applicants of any characteristics that could hurt their candidacy, experts say.

A federal district court sided with Elauf and her lawyers in the case, but she lost on appeal when the Denver, Colorado-based 10th US Circuit Court of Appeals agreed with Abercrombie.

The appeals court ruled that the 1964 act only protects employees who provide "explicit notice of the need for a religious accommodation."

The US Supreme Court, which usually sides with those who claim their religious freedoms have been violated, sharply criticized the appeals court decision, warning it "will lead to irrational results in other cases as well."

"Who bears the burden of initiating a dialogue as to any potential religious conflict?" asked Rachel Paulose, a former US attorney, in explaining the key question at the heart of the case.

"The EEOC argues the burden should be on the employer if it suspects a possible (religious) conflict, while Abercrombie argues... the initial responsibility (is placed) squarely upon the employee or applicant in every situation."

The case has received support from religious rights groups and US President Barack Obama's administration, which appealed the Colorado court's decision.

The EEOC said its cases involving complaints of religious discrimination have more than doubled in the past 15 years.

A decision by the high court is expected in June.