Breath testing devices of different styles and applications have been around since the late 1930s, and were introduced into mainstream policing of the roads since the 1970s. Breath testing devices work by checking the level of alcohol in your breath and then using a ratio of 1 to 2,100 — known as the partition ratio — to determine the level of alcohol in your blood.
Since the introduction of breath testing, many scientific studies have questioned whether the partition ratio is universally accurate, arguing that the ratio can actually range from 1 to 1,000 to 1 to 3,000. The physical condition of the person being tested can also impact the accuracy of the reading.
Despite these and other objections to breath tests, Nevada law requires that, if you are stopped by the police under reasonable grounds of driving while intoxicated, you must submit to a preliminary breath test of your blood alcohol level. If you do not willingly provide a breath sample, the police can seize your license, arrest you and take you in for additional tests, such as the more invasion urine and blood tests. The officer can use reasonable force to obtain samples.
If you refuse to take a breath test, the prosecution may decide to use this as evidence against you in court — as long as the police officer complied with all procedural requirements correctly. A skilled defense attorney can defend you against a DUI charge by looking into:
Malfunction of the breathalyzer machine
Lack of or expiration of a breathalyzer operator license
Use of an unapproved breath test device