Some states allow smiling in driver's license photos; others do not. The reason is that the facial recognition software that some states use to reduce fraud is better at matching unsmiling faces. Other states say smiling does not present a problem for their facial recognition software.
As of 2009, Virginia had banned any form of smiling in its driver's license photos. Arkansas, Indiana and Nevada allowed slight smiles, but not full grins. Pennsylvania was one state that continued to allow smiling, as its facial recognition software did not require a neutral expression to match faces. States such as Iowa and Delaware also adopted the policy, but Delaware began allowing smiles again as of January 2015, after upgrading its software.