Wal-Mart Stores Inc has recently sued Visa Inc. unveiling the latest legal battle over chip-enabled plastic money. The legal fight is for the right to choose how its customers can verify debit-card purchases at the store's checkout counters.

The retail chain wants its customers to use their personal identification number to verify their purchases when they use a chip-enabled debit card.

Wal-Mart's lawsuit filed in New York state court on Tuesday stated that Visa has prohibited it from requiring PINs only. This condition forced the store to permit customers to use a signature for their transactions.

This lawsuit is the latest legal battle between the two companies. They have sued each other a number of times over a variety of payment issues. The present legal tussle portends a continuing debate on how to harmonize convenience and security with the latest generation of chip-enabled cards.

"PIN is the only truly secure form of cardholder verification in the marketplace today, and it offers superior security to our customers," said Randy Hargrove, spokesman for Wal-Mart.

"Visa has acknowledged in many other countries that chip-and-pin offer greater security. Visa nevertheless has demanded that we allow fraud-prone signature verification for debit transactions in our U.S. stores because Visa stands to make more money processing those transactions," he added.

These chip cards are now being preferred in debit card transactions since they are much more difficult to hack since they create one-time codes to process every transaction.

Verification of transactions can be done either through a signature or a PIN, and those in the retail industry argue that requiring PINs from customers is more secure.

Merchants and shoppers alike are now in a transition period at the check-out counter. They both have to adjust to the more secure chip cards that most banks are now providing their clients.