Tommy Thompson is a former deep-sea treasure hunter and is about to mark his fifth year in jail for contempt of court for refusing to disclose the whereabouts of 500 missing coins made from gold found in an historic shipwreck. The normal maximum to hold someone is 18 months, so we are well past that. 

Can the courts hold someone indefinitely for contempt of court? 
When would this situation be considered 'cruel and unusual' punishment?