Not mandatory, you can refuse. Refusal in some states is an automatic suspension. Sobriety Tests fall under the Implied Consent Law" which you probably signed without reading when you got your license. You agree that by accepting the license that you will submit to a test upon an officer's request. If the officer concludes that he has probable cause , ie, smell. behavior, slurred speech etc, he /she will arrest you.
You do not need a lawyer, but whatever you do...do not hire one of the companies that advertise on TV or the net to "settle for pennies." You can contact the Taxpayer Advocate's Office and file a Form 911. If you have been unsuccessful in getting help through normal IRS channels, the Taxpayer Advocate can help. It is likely an illegal alien is using your husband's SSN to work in America. I have found that situation to be the most common when an SSN is used by another.
I have included a link to Form 911. I also have a link to help you find the Taxpayer Advocate Office for your area.