I have had difficulty obtaining death certificates from a few U.S. states, in particular New Jersey, Pennsylvania, and New York. Many states ensnare researchers in a genealogical Cache22: you have to submit proof that you are related to the person whose death certificate you are seeking--which of course is why you want the record, so that so that you can verify that you are related to the deceased.
New Jersey adds to this identification problem another twist: the state usually redacts the cause of death. Recently, the point of my research was to determine if certain diseases ran in a family. Even if I could submit the proper proof of descent (which I could not), I was told I could not see the cause of death.
So, off I went to the surrogate's court in the county of the person's death. Viola! A non-redacted death certificate, plus full access to the entire probate file!