WASHINGTON — The Supreme Court announced on Monday that it would decide whether a federal law prohibits employers from discriminating against gay and transgender workers. The law, Title VII of the Civil Rights Act of 1964, forbids employment discrimination based on sex. The question for the justices is whether that language bars discrimination based on sexual orientation or transgender status. Most federal appeals courts have interpreted the law to exclude sexual orientation discrimination. But two of them, in New York and Chicago, recently issued decisions ruling that discrimination against gay men and lesbians is a form of sex discrimination….