How is this supposed to clear the wrongly convicted?
If you are wrongly convicted, you wont have much issue providing your own DNA to get free.
This has only a few applications:
With current technology a matching genetic pattern can be generated. This would make a great tool for acquiring genetic patterns for the fabrication of evidence and false convictions. Even without such fabrication, genetic evidence can be abused to implicate someone that just happened to have passed through the location of a crime days, weeks or months before the event.
The theory is that if the person that actually committed the crime has a DNA sample in the system already then you will never be convicted in the first place. Or if you have already been convicted and they later get a sample that matches, from the newly expanded reasons for taking a sample, you are set free. This has already happened several times in rape cases in California. The individual was convicted even though the DNA was not a match. Then years later they take a DNA sample on an unrelated case, it matches the DNA from the previous case and they let the innocent guy out of jail.