If a case or lawsuit has not been filed before you move overseas, the bank will have to bring suit in a foreign country’s court of law and abide by the rules and procedures. The bank will have to hire a counsel in that area. A person would have whatever rights and defenses he would usually have.
But the bank’s success would depend on the country’s legal system and whether it would cooperate with them. In addition, it may be difficult to locate a person who is living abroad, although there are companies that will provide international skip trace services in certain countries.