Biometrics identifies/verifies a person using his/her physiological or behavioral characteristics. It is becoming an important ally for law enforcement and homeland security. However, there are some safety and privacy concerns: biometrics guarded system can be accessed when users are under threaten, reluctant or even unconscious states. In this paper, we propose a new concept, consent biometrics, which incorporates a consent signature based on human behavioral information. The proposed consent biometrics allows users to register their consent signature. When performing identification, the consent biometrics system will measure whether users consent to access the biometric system as well as perform biometrics identity match. In this way, the consent biometrics system can enhance the security, protect users from unauthorized access to the biometric system and discourage criminals to harm/threaten biometric users to some extent. We also propose two schemes that can realize the consent biometrics idea, and present example designs using face recognition and iris recognition as examples of these two schemes, respectively. The experimental results show that consent biometrics cannot only detect the willingness of users, but also achieve high recognition accuracy.