In an abstract of their paper Dan Frumkin, Adam Wasserstrom, Ariane Davidson and Arnon Grafit describe techniques that they say could be performed by any competent Biology undergraduate.  These techniques could be used to sample DNA (for example from the edge of a coffee cup or a cigarette) and then amplified via very standard techniques to be then to combine with refined red blood cells to create an entirely believable blood sample.

Interestingly, because red blood cells contain no DNA, they can be combined with DNA samples from the 'wrong' gender without detection.

In fact the scientists did just that.  They manufactured a variety of samples and submitted then (effectively anonymously) to a US-based forensic laboratory.  The results were entirely as expected.

Alternately, the scientists offer the possibility of creating a saliva sample.  Let's see if your lawyer can defend against either of those!

However, right now, all is not lost.  Frumkin et al have developed a test to refute their own findings.  Quoting from the abstract, "in natural DNA, some loci are methylated and others are unmethylated, while in artificial DNA all loci are unmethylated."  In this instance, the term 'loci' is simply a reference to abstract points of reference within the DNA sample.

The authors make a strongly worded suggestion that all DNA labs should apply the authentication assay to all samples to confirm their validity.

Right now, Gattica is still in the future, but for how much longer?