You are able to sue someone in Italy using proper legal procedure. My Lawyer in Italy can give you proper advice in choosing the correct court and filing papers within legal time limits which will give you a real chance to win your case.
Generally, you can be sued in Italy if you are in the country. It is harder to sue you if you are physically in a different country. If you own or run a business in Italy or own a property in Italy, that makes it easier for you to be sued before an Italian court.
Every case is different and much will depend on the facts.