How can an inmate do a paternity test?

The rules for this will vary depending on what facility the inmate is at. If it is court ordered fordetermination of paternity (most often for custody or child support issues) then the facility would be very likely to perform the test (even more likely if an outside source is paying for it). It is just a simple swab test that can be done in any clinic setting. However, if the inmate is requesting the test without a court order, it will likely be much more difficult. In the case of the inmate requesting it, I would imagine that his sentence being served would play some factor in it. The facility might want to make him wait until he is close to release if they'll do it without a court order at all. Also, in many states if you've ever committed a felony they require that your DNA be part of your record. I'm not sure if it's possible to go this route, but everything's worth a chance when it comes to kids. There might be a way of using that DNA sample to establish paternity. That would require: the inmate's consent (in the case of no court order), the judge's permission, the ability of whatever testing facility, and availability of the sample for things like this.