How?  According to Bill Hoidas at Matrix Payment Systems, with the new EMV Chip card regulations for face to face transactions, if a merchant swipes the mag strip on a chip card instead of using the chip function on their credit card terminal or POS and they receive a chargeback for any reason, no chargeback replies will be accepted by the card issuing banks.

They will automatically reject the chargeback reply and give Reason Code: "4870-CHIP LIABILITY SHIFT".  Be warned!

Bill Hoidas
Consultant Manager, Larger B2B/MOTO/Internet Accounts
Product Development Manager, Matrix Payment Systems