Well, the Food Police
- and their National Center for Home Food Preservation
website) currently say 1-year. If properly canned (that includes the entire process starting from washing the tomatoes to processing in the water bath/pressure canner) and stored in a temperature stable cool (about 40ºF), dry, dark place you could extend this up to 18-24 months - although this is going back to some Extension Service literature from 5-10 years ago.
Not only is bacteria a problem - the quality of the food (texture, color, flavor and nutrition ... especially vitamins) suffers greatly after a year.
I hate to throw away food ... and it's even harder when it is something I've canned because I'm not just throwing away food, I'm also throwing away time and effort. However, in the case of something canned in the 2002 season, I think I would toss it out.
As Katie noted - commercially canned food has a longer shelf life than home canned foods due to differences in processing.