What is the primary reason for conducting a breathalyzer test during a traffic stop?

The primary reason for conducting a breathalyzer test during a traffic stop is to measure blood alcohol concentration (BAC). Law enforcement officers use this tool specifically to determine whether a driver has exceeded the legal limit of alcohol in their system, which can impair their ability to operate a vehicle safely.

When a breathalyzer test is administered, it calculates the amount of alcohol present in a person's breath, which is then used to estimate the BAC. This information is crucial because it helps officers make informed decisions about whether a driver is under the influence of alcohol and poses a potential danger on the road.

The significance of BAC measurement is rooted in its implications for road safety and public health. States have established specific legal limits for BAC, and exceeding these limits can lead to serious consequences for the driver, such as fines, license suspension, or even incarceration.

The other options involve processes or checks that are not the primary purpose of a breathalyzer test. For instance, checking for illegal drugs or assessing driving skills does not directly relate to the function of a breathalyzer, while verifying vehicle registration is entirely separate from assessing a driver's sobriety.