Denver DUI lawyer / the chemistry of PBTs

I've written here before about portable breath tests. These tests serve an important role in establishing probable cause for a police officer to arrest a suspect. The other day while researching an issue unrelated to being a Denver DUI lawyer (I swear!) I found an interesting piece on the chemistry that goes in to these portable breath tests. Denver DUI lawyers generally know that these roadside handheld tests are bunk. Even the more accurate Intoxylizer that is used at police stations in Colorado has a fairly decent margin of error. However, here's further evidence that the portable breath tests are fairly unreliable (the whole thing on hangover chemistry is fairly interesting, though they get into the part about PBTs somewhere in the middle of the second video.

The essence of the good professor's point is this. Basically even though the PBT is able to spit out a number for an estimated BAC, there are a ton of different things going on to get that number. First, the alcohol in the breath combines with a chemical in the PBT tube to form a compound. This chemical creates some sort of orange hue on a cotton swab inside the the tube. Theoretically, the "oranger" the hue the more concentrated the alcohol in the breath. However, a burp, mouthwash, recently consumed alcohol and other things can throw off the reading. These are all places a good Denver DUI attorney can attack the probable cause from the PBT and possibly get the case thrown out.

The machine then automatically has to figure out how "orange" the cotton swab has turned. It then gives the operator a number down to the nth decimal. Now how exactly a machine that fits in your back pocket is supposed to look at a piece of cotton and decide how orange it is, then give a number down to the 100th of a percent or something is something of a mystery for lay-people and Denver criminal defense lawyers alike. But somehow the machine does it. And somehow this method gets a lot of people arrested, along with the roadside sobriety tests, which I'll talk more about later.

In any case, the PBTs are an unfortunate fact of life for people charged with DUI.