Facebook, Google and Apple are among the 76 companies asking the Supreme Court to hear a case involving a woman who was sacked because she's a lesbian.
"The U.S. economy is strengthened when all employees are protected from discrimination in the workplace", they said. The Savannah security guard sued her former employer Georgia Regional Hospital, claiming she was harassed at work and forced to quit because she is a lesbian.
Schneiderman led an amicus brief filed with the U.S. Supreme Court by 18 Attorneys General, arguing that employment discrimination on the basis of sexual orientation violates Title VII of the Civil Rights Act.
Two sports teams, the Tampa Bay Rays and the Miami Heat, also signed on to the brief, as did American Airlines, eBay, Starbucks and Microsoft.
The ruling "has wide-ranging, negative consequences for businesses, their employees and the USA economy", the companies told the Supreme Court in a friend of the court brief.
The businesses' court filing says they and their employees would benefit if the court agreed to take the case and rule that Title VII covers sexual orientation discrimination.
The lack of nationwide recognition that Title VII bars such discrimination blocks the full protection of LGBTQ workers - particularly given divisions between the Equal Employment Opportunity Commission (which takes the position that Title VII protects workers from sexual orientation) and the federal Department of Justice (which has taken the opposite position).
The companies argue that excluding sexual orientation from Title VII undermines the nation's business interests. Most federal appeals courts in the past have ruled that "sex" means biological gender, not sexual orientation.
Greg Nevins, a lawyer with Lambda, confirmed that the organisation would appeal the decision. President Donald Trump's administration has taken the view that it does not.
The groups noted that while 23 states and the District of Columbia protect workers from discrimination based on sexual orientation, the remaining 27 states do not offer explicit protections.
"We believe in treating every person we come into contact with - whether it's our employees, our consumers, or our vendors - with dignity and respect", said Anna Walker, Senior Director for Global Policy and Advocacy at Levi Strauss & Co.
"Employment discrimination based on sexual orientation (a form of sex-based discrimination) is widespread and has significant, harmful effects on employers, employees, and the bottom line", the brief states.
A group of 76 companies submitted a brief to the court saying a split among lower courts on that question had created uncertainty for employers and gay workers.
The 2017 report saw the largest increase in businesses in the history of the survey, 515 employers, earning ideal scores.