I just had two sets of passport photos taken, one at work and one at the local Costco. Both photographers told me not to smile in my photographs: that they could get rejected by the State Department’s passport processing if I were smiling. I thought that was ridiculous but to hear it from two photographers made me wonder.
Checking the Internets, I see there are differing opinions on whether this is a legitimate requirement. A few web forums say smiling is (and is not) allowed. The U.S. Consular Services in Canada office (where one would expect to find the official word) says you may smile if you wish.this is because smiling breaks the facial recognition software. Now, I would think any facial recognition software that can be defeated by the bad guy smiling isn’t worth much. I chalk it up to more security theater.
Interestingly, the Costo guy asked if my photograph was for a U.S. passport or a Canadian one. Apparently you can still smile in your Canadian passport photographs. No wonder Canadian travelers get better welcomes than Americans.