Believe it or not, some employers still want to respond to inquiries by potential employers of former employees. Do not give in to the temptation! While it is true that New Jersey has a qualified privilege for statements made by former employers about their former employees, you do not want to be in the position of having to justify comments you make about former employees.
Further, most employers these days are familiar with getting nothing more than “name, rank, and serial number,” so you will not be discrediting former employees by severely limiting information. Carefully limit what you say, and you won’t live to regret it.