Short answer: yes
It depends on what type of image it is. There are images that are in the public domain, which you can search out.
If you can make out a face, then you need to either
a) have gotten the release from the person
b) acquired it from photographer/agency/company who got the rights.
That being said, nobody called Obama to get the rights to use his picture to sell Grants, or Oprah and Rachel Ray to sell Acai.
We have gotten C&D orders for images that where not properly licensed. Now we insure that all images are legit.