Houston DWI task force getting mobile.

A bit like Bruce Wayne in Gotham the Houston Police Department is rolling out a DWI mobile van this Halloween weekend. The van is being hailed as the first of its kind. The Houston Police Department even expects to have several more of these vans on the streets soon.
I imagine the samebreathalyzer machine will be used in these vans. If so, will the machine's owner release the software pertaining to how the machine works. If a machine is going to brand someone a criminal and effect their life so much the accused deserves to know how it works. Typically, prosecutors say that it is a trade secret of the company that makes the machine. That poses the question what is more important, the trade secrets of a company or the constitutional right to due process, which surely includes the right to examine a machine used to determine if someone is guilty?
If you take the route of refusing to take the breath test you are not out of the woods. The DWI van is equipped for a quick warrant to be faxed in where an on-call judge can force the involuntarily draw of blood from the accused. Does that mean that the van will have nurses ready to draw blood? How well will the Houston Police Department be able to preserve the evidence? We all know how well the Houston Police Department has handled important evidence in the past.