Originally posted by Pilot Doc
Residents are free to quit at any time, regardless of the program's wishes. (Since the passage of the 13th amendment, this is true of any job.) A program could sue for breach of contract damages. However, they cannot make a resident stay nor can they prevent a resident from taking another job (i.e. residency.)
Also, most residency contracts run year to year, so a program would have zero recourse should a resident decide not to resign.