Final answer:
Sexual harassment is considered illegal discrimination based on sex according to the Civil Rights Act of 1964 and Title IX.
Step-by-step explanation:
The legal basis for considering sexual harassment to be illegal discrimination is that it is a form of sex discrimination. According to the Civil Rights Act of 1964, sexual harassment is considered unwelcome sexual conduct that creates a hostile working environment or interferes with a person's performance. This type of discrimination is prohibited in the workplace by the Act and in colleges and universities that receive federal funds by Title IX.