It shall be unlawful and constitute a Class 1 misdemeanor for any employer or any person acting as an agent for an employer, or any person who, for a fee, refers an alien who cannot provide documents indicating that he or she is legally eligible for employment in the United States for employment to an employer, or an officer, agent or representative of a labor organization to knowingly employ, continue to employ, or refer for employment any alien who cannot provide documents indicating that he or she is legally eligible for employment in the United States. Permits issued by the United States Department of Justice authorizing an alien to work in the United States shall constitute proof of eligibility for employment. All employment application forms used by State and local governments and privately owned businesses operating in the Commonwealth on and after January 1, 1978, shall ask prospective employees if they are legally eligible for employment in the United States. The provisions of this section shall not be deemed to require any employer to use employment application forms.