Final answer:
Employment discrimination is the illegal treatment of federal employees based on protected categories including race, color, religion, sex, national origin, sexual orientation, or gender identity, and is prohibited by Title VII of the Civil Rights Act of 1964 and subsequent legislation and court rulings.
Step-by-step explanation:
The term that describes the illegal treatment of federal employees due to their race, color, religion, sex, national origin, sexual orientation, or gender identity is employment discrimination. Title VII of the Civil Rights Act of 1964 prohibits employers from discriminating in various aspects of employment, such as hiring, firing, and compensation. Furthermore, the act was expanded to include the prohibition of discrimination based on pregnancy through the Pregnancy Discrimination Act of 1978 and, more recently, discrimination based on sexual orientation and gender identity following a 2020 Supreme Court ruling. Despite legal protections, there have been historical instances of systemic discrimination, like during the Lavender Scare, where several thousand federal employees were fired due to their sexual orientation.