This was actually heard in a courtroom:

Q: Doctor, before you signed the death certificate, did you check for a pulse?
A: No.
Q: Did you check for blood pressure?
A: No.
Q: Did you check for breathing?
A: No.
Q: So, then it is possible that the patient was alive when you signed the certificate?
A: No.
Q: How can you be so sure, Doctor?
A: Because his brain was sitting on my desk in a jar. But now that you mention it, it is possible that he could have been alive and practicing law somewhere.