I understand this is an old thread but things need to be clarified here:
Expiry Dates are for foods that are potentially hazardous i.e. fresh meat, fish and soft moist foods with minimal heat treatment that can harbour pathogens even when stored in cold temperatures (potato salad, vacuum packed cold cuts, store made uncanned pasta sauce). The time varies from a couple of days to a couple of weeks. Standards are set by the FDA according to the type of food, pH and water activity.
There are Best Before dates: they represent the approximate date where a non-hazardous food product, if store correctly according to the manufacturer's guidelines, may become altered organoleptically (taste, smell, colour, texture,...) outside a standard that the manufacturer has set as acceptable. These dates range from 3 months to up to 2 years (I think the latter is the maximum)
The FDA imposes that EVERY food has an <end> date so that Food providers may implement a FIFO program (First In First Out) and it can be monitored by a 3rd party inspection.
Any and ALL canned foods (either high or low acid) are <Commercially sterilized> using high temperature and pressure. There are strict time tables to follow. It is the manufacturer's responsibility to ensure that every single canned products they sell are sterile by implementing a tight HACCP monitoring program.
In conclusion: Legitimate canned foods means they are processed correctly and will never have any microbiological activity even after their best before date. (they are eternal). That said it is the sellers responsibility (the grocery store or distributor) that canned foods remain undamaged: free from corrosion, dents, leaks and punctures (a contamination hazard by micropore infiltration)
@French Fries is correct here.