Kudos to Walmart for standing up for better security options for their customers.  To put it bluntly, signature is not a security feature.  Pin should be an option for retailers to deploy and require as a security feature.  EMV deployment is not optional, so why shouldn’t a secure implementation be on the table for retailers that want to enforce good practices.

http://www.tripwire.com/state-of-security/latest-security-news/wal-mart-sues-visa-over-chip-debit-card-transactions/