True.
Under U.S. federal law, it is illegal for an employer to knowingly hire or continue to employ an unauthorized immigrant. This is outlined in the Immigration Reform and Control Act (IRCA) of 1986, which requires employers to verify the identity and work eligibility of all employees hired after November 6, 1986, by completing and retaining a Form I-9. Employers who knowingly violate these laws can face significant fines and legal penalties.
I hope I helped!
~~~Harsha~~~