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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 Tag: criminal defense Austin

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.

You may not go to jail for pot possession in Austin, but you can’t ignore the ticket

Chris Perri

It’s a beautiful December day in Austin, and Sue, a student at the University of Texas, wants to celebrate the end of the semester with friends at the Greenbelt. While relaxing in the 70-degree weather near a swimming hole, one of Sue’s friends lights up a joint. Sue doesn’t usually smoke pot, but she’s cutting loose today, so she closes her eyes as she takes a long drag off of the joint, the stresses of the semester exhaling out of her with the sweet smoke of her friend’s kindbud. She then opens her eyes, and her momentary relaxation gives way to full-fledged panic as she spots a uniformed police officer on a bicycle stopped on a nearby trail. The officer calls out for her to bring him the joint. Sue’s mind and heart race, as she remembers what happened to her older brother in their small town where he was arrested for marijuana possession and spent the night in jail.

The cop sternly warns Sue about the illegality of smoking marijuana: “This isn’t Colorado, young lady.” However, to her delight, he bikes off after handing her a citation that looks almost exactly like a speeding ticket. Sue can’t believe her luck in not getting arrested! Maybe she won’t even have to tell her parents. There’s a date listed on the ticket to report to “Justice of the Peace – Precinct 5” on December 22. Sue’s going to be back home for the holidays by then, so she later tosses the ticket on a stack of old books in her apartment, figuring that she can just deal with it when she returns to school in January for the spring semester.

 

Given that the ticket doesn’t look a whole different than a traffic citation, it’s understandable that Sue might think it’s no big deal. In reality, Sue’s offense is a class B misdemeanor, which is punishable by up to 180 days in the county jail and a $2,000 fine. Unlike most counties in Texas, where you’ll be cuffed and carted off to jail for anything worse than a class C misdemeanor traffic offense, Travis County is different. Here, the police are authorized to issue tickets for misdemeanor marijuana possession (four ounces or less), along with a few other class B misdemeanors (driving with license invalid, theft, graffiti, criminal mischief). These tickets are called “field-release citations” because the police release the defendants without booking them into jail. The rationale behind this policy is that arresting people takes several hours, resulting in fewer police officers patrolling the streets.

However, just because Sue received a citation doesn’t mean that she’s avoiding an arrest record. Instead, the arrest occurs during what is called a “jail walkthrough” when Sue reports to the Justice of the Peace at the time designated on her ticket. Below, I’ve outlined the steps of the process:

1.     Report to Justice of the Peace – Precinct 5 (located at 1000 Guadalupe Street in downtown Austin) to receive paperwork and instructions about the walkthrough process.

2.     Report to Pretrial Services in order to apply for a personal bond.

3.     Return to the Justice of the Peace, who will magistrate the defendant, meaning that the defendant is informed about constitutional rights and the penalty range of the offense.

4.     Obtain approval of the personal bond from the Justice of the Peace.

5.     Report to the Travis County Sheriff’s Office at their bonding desk in the courthouse.

Upon reporting to the sheriff, Sue is officially arrested. The sheriff’s deputy would take her fingerprints and a mugshot. Sue would then be released from custody without ever being handcuffed. She would also receive a copy of her personal bond with a court date.

Following this “arrest,” Sue’s case would be assigned to one of the county courts-at-law, and her lawyer could then begin resolving your case by requesting discovery materials (offense reports, video/audio of the incident, etc.) and negotiating with the prosecutor.

Like many people issued similar citations, Sue doesn’t immediately realize the importance of reporting to the Justice of the Peace on the date and time designated on the ticket. This is a very bad idea because failure to appear results in an arrest warrant. There is no “jail walkthrough” for Sue if she is later arrested on a warrant, and the process of getting booked in and out of jail would take 12-24 hours. Her initial fear of spending a night in jail would become a reality.

Here’s what Sue should do immediately upon receiving the citation: contact an experienced attorney, such as Chris Perri Law, to assist her with the jail walkthrough process. An attorney can waive the third step of the process (magistration by the judge) in order to ensure that Sue is one of the first people to report to the sheriff’s office for the booking procedures. Often, Chris Perri Law can get somebody through the entire process in less than an hour. Without an attorney, the process can take up to four hours because there’s often a long line of people with similar tickets, and the sheriff’s office only has two deputies (at most) working on the walkthrough process at any given time.

Chris Perri Law also would assist Sue in resolving her case in a manner that leads to an eventual expunction of her arrest record. Even though Sue might feel like she was never arrested because the jail booking procedure was so quick, information about the offense is automatically forwarded to the Department of Public Safety (DPS), who enters it into their crime records database. Background checks will reveal the incident unless Sue successfully expunges the records of the arrest. Given that she’ll be graduating from UT and on the job market in a few years, it’s very important that Sue hires an experienced attorney who knows how to ensure that her arrest record from this incident is ultimately wiped clean.


***Sue is not a real person.

Wrongful convictions may have have resulted from crime labs' exaggeration of DNA results

Chris Perri

 

Austin news station, KXAN, interviews Chris Perri about the issue. 

Over the summer, the Texas Forensic Science Commission, which reviews the current standards for physical evidence in Texas criminal courts, discovered that state crime labs were using outdated protocols for analyzing DNA evidence. In particular, the problems occurred in “mixed DNA” test results, where the labs were exaggerating the likelihood that a particular sample matched a defendant’s DNA.

There are two types of DNA profiles that can come from any given DNA sample: “mixed DNA” (also called “mixtures”) and single-source DNA. Mixtures are the most common type of DNA profiles. A mixture occurs when a DNA sample contains DNA from more than one person. For example, if two or more people touched the handle of a firearm, a DNA sample from this handle would likely be a mixture of multiple people’s DNA. In contrast, a “single source” DNA profile exists when only one person contributed the DNA to a sample. In the case of single-source DNA profiles, matching a given person to the sample is similar to matching a person to a fingerprint left at a crime scene. However, because there are numerous types of DNA profiles that could combine to create a mixture, the probability that a random person besides the defendant could have contributed to this mixture is higher than in the case of single-source DNA profiles.

The Texas Forensic Science Commission recently revealed that state labs have been reporting inaccurately high probabilities of matches between defendants and mixed DNA samples since 1999.

An example of a recent Galveston murder case illustrates the problem. The crime lab reported that the defendant contributed DNA to a mixture from the crime scene, with a certainty of more than a million to one. However, it turns out that the lab was using outdated protocols, and the certainty is actually just forty to one. This means that if you selected 1,000 random people, 25 of them would match the DNA found at the crime scene. That’s hardly enough evidence to convict someone beyond a reasonable doubt.

Everyone knows that eyewitness testimony can be fallible, so prosecutors have placed great weight on scientific DNA evidence when prosecuting cases since the advent of DNA testing in the mid-1990s. Due to jurors learning about the infallibility of DNA science from television crime shows (the CSI effect), jurors often convict defendants on the basis of DNA evidence alone. Now that we know that scientists were inaccurately reporting the probability that crime scene DNA matched particular defendants, many convictions over the last fifteen years may have been based on false evidence, and innocent people could be behind bars.

Police labs and prosecutors’ offices have downplayed the severity of the problem. For example, according to a memorandum from Art Acevedo, the chief of the Austin Police Department, the inaccurate reporting is “unlikely to materially affect any assessment of evidential value.” Court orders will be required in order for the labs to re-test samples to determine accurate statistical probabilities of a match between crime scene samples and defendants’ DNA.

I’m concerned that prosecutors and police forces are sweeping this issue under the rug. Rather than re-assure the public with rhetoric, they should create task forces to revisit every case where DNA played a role in obtaining a conviction, and the labs should recalculate statistical probabilities in all of those cases. After all, it was the State that put false evidence before juries, so the burden should be on the State to correct the problem and regain the public’s confidence that innocent people aren’t behind bars.

If you or a loved one suffered a criminal conviction as a result of mixed DNA test results, you should contact Chris Perri Law to determine whether your case could have been affected by inaccurate scientific testimony. Check out the articles below for more information on this unique and unsettling issue:

http://www.everythinglubbock.com/news/state-regional/new-dna-standards-could-lead-to-thousands-of-retrials-in-texas

http://www.npr.org/2015/10/09/447202433/-great-pause-among-forensic-scientists-as-dna-proves-fallible?utm_source=facebook.com&utm_medium=social&utm_campaign=npr&utm_term=nprnews&utm_content=202509

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.

Chris Perri Gives His Take on Life Imprisonment for Habitual DWI Offender

Chris Perri

A recent ruling by the Third Court of Appeals of Texas states that a life sentence can be a reasonable punishment for a third DWI felony conviction. 

In 2012 a woman in San Marcos was arrested and convicted for her third felony DWI—her sixth DWI conviction total. The case was tried in front of Hays County Judge Jack Robison, who found her guilty with a punishment of life in prison. The woman’s attorneys attempted to appeal this sentence, arguing that life in prison for a DWI violates the Eight Amendment—a cruel and unusual punishment. However, a three-judge panel of the Third Court of Appeals upheld Judge Robison’s sentence, holding that she had a dangerous pattern of behavior and was a habitual offender. (For more about the case, click here.)

“Though saddening that this woman got to this point, I don’t necessarily believe the sentence was a violation of the Eighth Amendment,” Chris Perri says. “I do, however, feel this highlights the importance of connecting first- and second-time DWI offenders to the appropriate resources and working with the prosecution to incentivize defendants to seek rehabilitation. I don’t know the details or history of this case, but I can’t help but wonder if in some way the system failed her.”

Professional drug and alcohol treatment is not a 100% guarantee for relapse prevention, but it definitely can help shift the odds in one’s favor. That’s why Chris Perri Law tries to find the best legal outcomes for its clients that lead to life successes and reductions of repeat-offenses. When appropriate, part of his services include linking clients to community resources or advocating for clients to be referred to the Mental Health Court.

“If we don’t look at the whole person—his or her story—nothing’s going to change,” Chris Perri says.

This sad case proves that having a strong legal advocate who cares about your future and wellbeing is crucial. If you or someone you know is in need, call Chris Perri Law at (512)917-4378 today. 

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.