Ex-employee problems

[NeedInfo]

An ex-employee who left the company in March is now claiming that he was not paid for items he says he purchased for company use. Four weeks after he left my company, he sent me receipts that he wanted to be paid for. The company policy is that all purchases must first be approved by the owner and receipts submitted witin one week from date of purchase. Is this a valid defense in small claims court since most of the purchases he is claiming to have made are from January and February of 2007?