[LouD]

but this should only be allowed where this type of evidence was used to convict the person

Why? If there is DNA evidence which exonerates someone convicted of the crime, why would it matter if the evidence were used in his first trial? In this case, the point is that DNA technology was not availble for the original trial.

[umgud]

I was refering to cases based on this type of evidence. If the cops catch a bank robber in the act, there is little need to perform DNA testing. But I agree with you, that in any case where DNA could exonerate a person, it should be used.