I'm fairly certain such regulations don't exist anywhere. They would be far too easy to exploit, raising the cost of doing business and exposing them to outright fraud. Regulations meant to protect consumers usually protect them from dishonst business practices.

The type of return you're talking about is usually intended to encourage people to make a purchase and to protect the reputation of a business. Yet the moment they detect abuse, abuse being return patterns that are atypical or that will end up costing the business more money in the long run, you can be sure they will stop honouring their return policy.