In a friend of the court brief, the Trump administration stated that Title VII does not protect gay workers from discrimination, arguing that the federal law was only intended to ban sex discrimination in the workplace. Former President Barack Obama, as well as the the US Equal Employment Opportunity Commission, which enforces Title VII, have both long argued that the law also bans discrimination based on sexual orientation. The Justice Department defined sex discrimination only as employers treating male and female workers differently, while discrimination based on sexual orientation falls under moral or religious beliefs. A lawyer involved in the case currently being contested has said that the Trump administration is making the same arguments the Supreme Court has rejected in court cases involving discrimination of workers in interracial relationships.
See "U.S. Justice Department says anti-bias law does not protect gay workers", Lucy Nicholson, Reuters, July 28, 2017