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hris Perri Law is a criminal defense law firm located in Austin, Texas.

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Chris' Blog

The blog of Chris Perri Law, written by Chris Perri and Shannon Perri. Read the latest in exciting cases where justice is served.

Filtering by Category: Recent Cases

Breath Test Machines: Less Reliable Than You Think

Chris Perri

 Chris Perri, next to his very own breathalyzer.

Chris Perri, next to his very own breathalyzer.

In DWI investigations, breath test results are very common evidence. Although I advise clients to refuse to provide a sample of their breath, the case isn’t over just because the machine says that the sample is over .08 BAC.

At the outset, it’s important to realize that BAC means blood alcohol concentration, not breath alcohol concentration. Breath test science relies on the assumption that it can obtain a reliable breath alcohol concentration that mirrors a particular person’s blood alcohol concentration. This assumption is fraught with difficulties, as I’ll explain below.

Let’s start with a very simplified description of the mechanics of the breath-test machine (also known as an intoxilyzer or breathalyzer). An arrested person blows into the machine, which takes this breath sample and shoots it through a tube that’s then injected with infrared light. Because alcohol particles block infrared light, the machine detects the amount of alcohol in a subject’s breath by determining how much of the infrared light has been blocked. It then takes this number, makes some calculations, and reports a breath alcohol concentration.

The calculation of this breath alcohol concentration is problematic because there’s a lot less alcohol in the breath than in the blood. For example, in an average person, the number of grams of alcohol in 1 part of the blood is equivalent to the number of grams of alcohol in 2100 parts of breath. This 1:2100 ratio is known as a “partition rate.” So, while a person’s blood alcohol concentration is defined as the number of grams of alcohol in 100 milliliters of blood, that same person’s breath alcohol concentration is defined as the number of grams of alcohol in 210 liters of breath. (Note: 100 milliliters x 2100 = 210 liters). In other words, if you have .08 grams of alcohol in 100 milliliters of your blood, then it’s assumed that you have .08 grams of alcohol in 210 liters of your breath.

While it’s not hard for police to obtain 100 milliliters of your blood, it’s impossible for them to obtain 210 liters of your breath (think about a 1 liter bottle and imagine filling up 210 of those bottles with your breath). For this reason, the breath test machine must multiply any amount of alcohol that it detects by a very large number. As an example, if you provide the machine with one liter of your breath, then the machine multiplies the amount of alcohol it detects by 210 in order to determine the number of grams of alcohol per 210 liters of your breath. This calculation is then reported as your BAC.

Consequently, any error by the machine in determining the amount of alcohol in a given sample would be exacerbated when it multiplies that incorrect number by two-hundred-fold. Such errors can occur when the machine interprets non-alcoholic particles in the breath as alcohol. For example, the machine cannot distinguish acetone (a common substance in the breath of diabetics) from alcohol. Or, imagine the complication of a stray particle of liquid alcohol entering the machine in the form of spit. Any error in the initial measurement of alcohol will render the entire breath test unreliable.

 Photograph courtesy of Oregon Dept. of Transportation

Photograph courtesy of Oregon Dept. of Transportation

For my next point, let’s give the machine the benefit of the doubt and assume that it can accurately measure the quantity of alcohol in a person’s breath. Even then, the machine makes a critical and troublesome assumption: that the subject’s partition rate is 1:2100 (recall from above that this means that the amount of alcohol in one part of blood is equal to the amount of alcohol in 2100 parts of breath). This assumption is not true across the population, as studies show that partition rates of normal people vary from 1:1100 to 1:3000.

As an illustration, let’s take a hypothetical subject arrested for DWI and call her Sue. She has a partition rate of 1:1100, which means that the number of grams of alcohol in 1 part of Sue’s blood is the equivalent of the number of grams of alcohol in 1100 parts of her breath. On this particular evening, Sue has consumed enough alcohol that her BAC is .06 grams of alcohol per 100 milliliters of blood. Since her partition rate is 1:1100, there would also be .06 grams of alcohol in 110 liters of her breath (note: 100 milliliters multiplied by 1100 equals 110 liters).However, the breath machine is going to overestimate the BAC by nearly a factor of two. Here’s why:

When Sue takes a breath test, the machine is programmed to incorrectly assume that her partition rate is 1:2100. As a result, it will determine the number of grams of alcohol in 210 liters of her breath. Since Sue’s correct BAC is .06 grams of alcohol per 110 liters of breath (due to her partition rate of 1:1100), she has .11 grams of alcohol per 210 liters of her breath. Due to the machine’s inaccurate assumption that Sue’s partition rate is 1:2100 instead of 1:1100, the breath-test machine will report a BAC of .11, which is nearly twice as high as her actual BAC of .06. This inaccuracy results because the machine is improperly measuring the number of grams of alcohol per 210 liters of Sue’s breath, as opposed to the number of grams of alcohol per 110 liters of her breath. Thus, the machine’s assumption that everyone has a partition rate of 1:2100 creates a critical error by reporting that Sue is intoxicated even though she’s actually below the legal limit of .08 BAC.

Finally, it’s important to remember that it’s only illegal to be intoxicated while driving. It’s not a crime to be intoxicated 10 minutes, 30 minutes, or an hour after operating a motor vehicle. But these chemical tests usually occur over an hour after driving, and the prosecution has the burden of proving how that BAC measurement relates to the time of driving. Unless law enforcement knows a lot of information about a particular person (e.g., number of drinks consumed, when the drinks were consumed, the type of alcohol consumed, amount of food consumed, when food was consumed, etc.), it’s impossible to conduct a reliable retrograde extrapolation, which is the science of determining a past BAC level based on a known BAC level. In other words, if the breath test machine reports that a person has a .11 BAC over an hour after driving, we don’t know whether the person’s BAC at the time of driving was below, above, or the same as the level reported by the machine.

While breath tests are an important tool for law enforcement in that they give a ballpark figure about an arrested person’s intoxication level, it’s a common misconception that a breath test machine provides an exact measurement of a person’s BAC at the time of driving. If you or a loved one have been arrested for DWI and submitted to a breath test that reported a BAC over .08, don’t despair. Call an experienced criminal defense attorney to fight the machine’s potentially inaccurate result.

Suppression Victories Preserve Our Constitutional Rights

Chris Perri

Chris Perri Law is proud to share that we’ve won three suppression hearings so far this year.

For those who may not know, a suppression hearing is held when a defendant believes that evidence was obtained in violation of a constitutional right. If the court agrees with the defendant, then the evidence is “suppressed,” which bars the prosecution from using this evidence at trial.

For example, in our recent blog post, we discussed a Supreme Court case where officers seized drugs from a vehicle following a positive canine alert during a traffic stop. This issue was litigated at a suppression hearing, where the defendant won the argument that the police officer violated his Fourth Amendment rights.

In many cases, winning a suppression hearing directly leads to the prosecutor dismissing the case due to insufficient evidence. As a result, the public often misunderstands suppression as a legal loophole that allows criminals to avoid accountability for their actions. Chris Perri doesn’t see it that simply.

 “Suppression hearings are my favorite part of practicing law,” Perri says. “The fact that my clients were caught with incriminating evidence isn’t the whole issue. Instead, we’re focusing on whether the police followed the rules. And these aren’t just any rules – these are the foundational principles that glue our country together. If judges allowed evidence to be introduced at trials despite being illegally obtained, then what’s the point of the Constitution? It’s the real possibility of suppression that keeps the police in line when they investigate illegal activity. It’s a part of our system’s checks and balances of power.“

Chris Perri Law Suppression Win #1

Earlier this year a client faced felony cocaine distribution charges after a police officer entered his house without a warrant. According to the cop, who was at the defendant’s front door in order to investigate an anonymous tip, he witnessed our client flushing the cocaine down the toilet, and he entered in order to prevent the imminent destruction of evidence (an exception to the general requirement that a warrant be obtained prior to entering someone’s home). However, the blinds covering the windows were drawn, and the cop had to awkwardly peer up through a crack in them in order to observe the inside of the home. Chris Perri Law successfully argued that while Supreme Court precedent recognizes an implicit license for anyone to come to the front door to knock and briefly wait for an answer (example: Girl Scouts selling cookies), no one—not even a police officer—is invited to violate the homeowner’s right to privacy by bending down to peep through a crack in drawn blinds. In fact, if you saw someone on their knees under someone’s window, trying to peer in through the blinds, you’d probably call the cops. The reasonable Travis County district judge ordered that the evidence be suppressed.

Chris Perri Law Suppression Win #2

At our next suppression hearing, a client faced a DWI charge and sought to suppress the blood evidence that was obtained with a search warrant following his arrest. Because the blood analyst reported a BAC of nearly twice the legal limit, combating this evidence was critical to our case. Our goal was to demonstrate that the officer lacked probable cause to arrest our client (a Fourth Amendment violation), so any evidence derived from an unlawful arrest is subject to suppression. By cross-examining the officer with the video of the stop and presenting evidence that undermined the officer’s credibility, Chris Perri Law convinced the court to suppress the blood results. Subsequently, the prosecution dismissed the charge due to insufficient evidence.

Chris Perri Law Suppression Win #3

Finally, in a pending felony case, Chris Perri Law suppressed key evidence a police officer obtained before reading the client his Miranda rights. Details will have to wait for a future blog post so that we do not compromise the resolution of this case.

Chris Perri Law is proud to practice criminal defense in Travis County, where constitutional principles reign supreme. If you or someone you know has a potential suppression issue, along with any other criminal defense matter, contact us today at (512)917-4378.

The 5th Circuit Invites Chris Perri Law to Present Oral Arguments Once Again

Chris Perri

It looks like I’ll be heading to New Orleans early next year! I just received word that the 5th United States Circuit Court of Appeals has granted me the opportunity to present Oral Arguments on a federal felony appellate case.

This will be my second time to argue in front of the Fifth Circuit. To read more about my previous 5th Circuit Oral Arguments, click here.

I’m looking forward to the chance to fight in court, and I’m grateful to the 5th Circuit for finding the appeal worthy of their time. 



Court of Appeals Grants Chris Perri Law Oral Argument on Felony Case

Chris Perri

The Corpus Christi Court of Appeals has granted me the opportunity to present formal Oral Arguments on a felony DWI case in which my client was convicted and sentenced to twenty-five years in prison. At trial, during which I was not yet his lawyer, the main evidence of my client’s intoxication came from a warrantless blood draw, revealing that his BAC was over the legal limit. Just a few months after my client’s trial, the U.S. Supreme Court ruled that it was unconstitutional for an individual’s blood to be drawn during a DWI arrest without a warrant—even if it was the individual’s third DWI. At the time of my client’s arrest, however, Texas law allowed the police to draw a person’s blood without a warrant if that person had two or more prior DWI convictions. However, due to the fact that the Supreme Court’s ruling occurred while my client’s case was pending appeal, I’m arguing that this ruling should apply to his case so that his conviction is overturned and he can be retried without the tainted evidence. The interesting issue on appeal is that because the trial attorneys did not object to the admission of the blood evidence, no error was preserved. Usually, objections are necessary to present an appellate issue because appellate courts require that the trial judge had an opportunity to make a ruling. I plan to fiercely argue that even though the error was not preserved, it represents such a fundamental miscarriage of justice that the appellate court should still reverse the conviction. 

Chris Perri Convinces Prosecutor to Dismiss Assault – Family Violence Charge

Chris Perri

A few weeks ago, the Travis County Attorney dismissed an Assault – Family Violence case that had been filed against one of Chris Perri Law’s clients.  The case had been set for jury trial, but Chris convinced the reasonable prosecutor to dismiss the charge. 

The incident began when the client’s girlfriend accused him of cheating, and a struggle ensued over the client’s laptop computer.  The girlfriend’s brother happened to enter the apartment, and the client was soon double-teamed by the angry sibling duo.  Significantly, Chris’ client called 911 as soon as he was able to escape their violent assault, but the girlfriend immediately called 911, too, in order to concoct a story that incriminated the client.  When Chris saw the client in jail, he was banged up with welts on his face and arms, as well as bruises and cuts.  Chris also talked to the girlfriend, who stated that she would say anything to make the client stay in jail because she was angry that he had called the cops on her.

Chris emphasized that the 911 tape showed that his client had called the police first because he was in fear for his life.  Chris Perri Law also learned that the girlfriend returned to my client’s apartment months later and threatened to lie in court if my client did not reconcile with her.  This incident was documented in a separate police report, and Chris Perri Law requested that exculpatory evidence pursuant to the prosecutor’s obligations under Brady v. Maryland.  Most importantly, Chris Perri Law set the case for a jury trial to show that he and his client were ready to fight the case in court, if necessary.  The reasonable prosecutor then did the right thing by dismissing the case.

 

Not Guilty in Austin Municipal Court!

Chris Perri

“Not guilty.” Those are the two sweetest words that a criminal defense attorney can ever hear. Today, the jury returned this coveted verdict in a speeding trial at the Austin Municipal Court. Sure, it was just a speeding ticket. But for my client, who holds a commercial driver’s license (CDL), it was a very important case. Most people can easily get their tickets dismissed by taking a defensive driving course. However, under the law, anyone holding a CDL does not have this option. Instead, they must either fight the ticket or take a conviction. One of the most common misperceptions is that simply driving over the speed limit is against the law. In actuality, the law states that “an operator may not drive at a speed greater than is reasonable and prudent under the circumstances then existing.” See Tex. Trans. Code §545.351. I discussed this law with the jury panel during the voir dire process, and they were very surprised that there’s more to speeding than simply driving above the speed limit. As I pointed out to them, discovering the actual wording of the speeding law is analogous to finding out that there’s no such thing as Santa Claus.

There’s one wrinkle here: when the State proves that a vehicle was travelling over the speed limit, that’s “prima facie” evidence that the driver’s speed was not reasonable and prudent. I explained to the jury that this only means that if the State proves the speed was over the limit and I present no further evidence regarding the reasonableness of the speed, then I lose. But once I bring forth any evidence that the driver’s speed was reasonable, the State has the burden of proving the speed was unreasonable. Plus, this burden is a heavy one: “beyond a reasonable doubt.”

At the trial, we presented evidence that on the morning of the alleged speeding incident, my client was stuck behind a boat trailer on Highway 183. The boat was being hauled by an undersized pickup truck, and my client testified that he felt that the trailer was creating a hazard on the road. A car in front of my client passed the trailer, and my client followed suit. In order to do so, he had to increase his speed to about 78 mph on a highway that had a speed limit of 65 mph. Other vehicles behind my client also passed the trailer. I successfully argued to the jury that it could consider the other drivers’ behavior as evidence of the reasonableness of my client’s decision.

The State attempted to counter our evidence through the testimony of the police officer, who stated that my client was speeding before and after he encountered this boat trailer. The officer further testified that there was a curve on the road that made it unsafe to travel above 65 mph. The jury was unconvinced. After all, this was a dry day, and my client was a “professional driver.” He testified that he made a “judgment call,” and who was the jury to disagree with his professional judgment?

After about 20 minutes of deliberating, the jury returned its two-word verdict. My client exited the court triumphantly with his clean driving record intact.

No jail time, no convictions in marijuana transportation case

Chris Perri

Despite being caught transporting approximately 35 pounds of marijuana across the country, my clients won’t have to spend any time in prison after I worked out an excellent plea deal with the reasonable district attorney in Carson County, Texas. My clients were pulled over along I-40 in the Texas Panhandle, and we were prepared to contest the legitimacy of the stop unless we achieved a reasonable plea bargain. The driver was adamant that his passenger's case be dismissed due to the passenger’s lack of knowledge of the illegal contents of the trunk. Eventually, the prosecutor agreed, so the passenger’s case was dismissed, and he’ll be eligible to expunge all records of the arrest in about 2.5 years. Meanwhile, the driver won’t even have a felony conviction on his record because I worked out a deferred adjudication, meaning that as long as the defendant abides by the terms of his probation, a conviction won’t be entered in the case. The catch was that he had to pay over $6500 in various fines and court costs. Still, that’s a lot better than facing the penalty range of a third-degree felony (2-10 years in the state prison, which isn’t fun for first-timers).

Also, the outcome represents an implicit understanding that marijuana isn’t a terrible drug like methamphetamine, cocaine, or heroin. In fact, most of the people who were supposed to receive my clients’ marijuana were cancer patients who use it as medicine to help cope with the side effects of chemotherapy. Even though the expensive fines may seem quite harsh, that money will go to good use in the Texas Panhandle, as it can be used towards public goods, such as education and environmental initiatives. In the end, that’s a true win-win!

Marijuana charge dismissed

Chris Perri

The progressive Travis County Attorney’s Office dismissed my client’s possession of marijuana (POM) charge today in exchange for him pleading guilty to a lesser charge of possession of drug paraphernalia, which is a class C misdemeanor (same category as traffic offenses). All my client had to do was pay $172 in fines and court costs. In POM cases like this one, which was a class B misdemeanor because it involved less than two ounces of marijuana, the Travis County Attorney usually gives first-time offenders a break. The prosecutors recognize that a POM conviction results in the burdensome automatic suspension of an offender’s driver’s license for six months, which can often lead to someone becoming a repeat offender if they drive with the suspended license. Our prosecutors want to put these defendants in the best possible position to overcome their criminal charge, so they’ll usually dismiss the charge in exchange for the defendant completing a 15-hour drug education class and community service.

Now that police officers are permitted to issue “sign and release” citations whereby POM defendants aren’t booked into jail when they possess less than two ounces, marijuana possession could almost be said to be “decriminalized” for first-time offenders in Travis County, as they’re likely to have the charge reduced to the same grade as a traffic offense, which carries no possibility of jail time.

On the other hand, if you go up the road to Williamson County, the situation is much different. Even if you get caught with just a joint, you’re likely to be sentenced to 18 months probation, and if you violate any conditions of that probation, it’s not uncommon for one of the no-nonsense judges to slap you with a 90-day jail sentence.

Appeals court upholds suppression of evidence

Chris Perri

Last year, I successfully moved for the trial court to suppress the State's expert testimony regarding my client's blood-alcohol concentration (BAC) at the time of an alleged incident of Boating While Intoxicated. I wrote about this in my blog at the time. The State was unhappy with the judge's ruling, so it appealed. Today, a three-judge panel of the Third Court of Appeals upheld the trial court's ruling that the State could not introduce expert testimony on my client's BAC. The opinion can be read here. This is a great victory for my client, and I anticipate that the State will dismiss the pending charges due to the fact that it would not be allowed to present evidence of my client's alleged intoxication if the case proceeded to trial.

Another theft charge dismissed

Chris Perri

Today, the prosecutors dismissed my client’s pending charge of class B misdemeanor theft (the value of the stolen goods was between $50 and $500).  To obtain this dismissal, I worked out a deal where my client entered into a deferred disposition agreement on a class C misdemeanor theft charge (the value of stolen goods were less than $50).  If my client completes 20 hours of community service and stays out of trouble, that charge will be dismissed in six months.  She would then be eligible to expunge all records of her theft arrest two years from the date of the offense.  After expunction, she will be able to deny that any theft arrest ever occurred.

Theft charge dismissed

Chris Perri

One of my young clients was caught stealing from a local department store.  Despite the evidence against her, she was approved for a pretrial diversion program, and the charges were dismissed today.  As long as she succeeds in performing the conditions of the program (community service and avoiding further trouble with the law), she will be able to expunge the arrest two years from the date of the offense. For young clients, expunctions are extremely important, as they allow clients to deny that their arrest occurred when prospective employers or educational institutions question them about their criminal histories.

An expunction victory

Chris Perri

After two years of considering the case, the Third Court of Appeals in Austin decided in my client’s favor on an important expunction issue.  Prosecutors had been trying to prevent defendants from expunging their DWI arrests when they took probation on lesser charges (Reckless Driving or Obstruction of a Highway).  This was due to a strained reading of the expunction statute that I discuss more thoroughly in my blog.  The Third Court of Appeals accepted my argument that an expunction analysis should proceed by looking at each charge in isolation; as a result, a dismissed DWI is eligible for expunction regardless of what happens on another charge that stems from the same arrest.  This is a great victory for any defendant who uses plea bargaining to get rid of an unfair DWI charge. Remember, if you don’t get your charge expunged, potential employers can still see the arrest!