Having your vehicle’s speedometer calibrated may be helpful when you are defending against a reckless driving charge or a speeding charge. It is particularly helpful evidence to submit to a judge if you wish to testify that you had reason to believe you were driving slower than the speed you were alleged to have gone and the calibration results show your speedometer is off in the proper direction. A mechanic should run tests on your car and produce a notarized affidavit that is admissible in court. I send my clients to a mechanics shop that uses a computerized chassis dynamometer and have my clients mention to the mechanic the speed they were alleged to have gone so that the proper tests can be done. The speedometer certificate will show the test results for various speeds and show how much your speedometer display is off compared to the actual speed of the car. My clients are often surprised by how much their speedometer is off, even if the car they drive is relatively new.
Depending on the court and the judge, often a judge or prosecutor may amend your speed to reflect the speed shown on your speedometer. So if you were charged with reckless driving by speed, and the officer states that you were going 77 mph in a 55 mph zone, a calibration showing that your speedometer was lower than your actual speed by 3 miles per hour would bring you to 19 mph over the speed limit. This would be enough to get you out of the reckless driving criminal misdemeanor category and into the speeding category. Getting a calibration done is not a waste of money in most situations where your alleged speed is close to the twenty or more miles per hour over the speed limit required to get a reckless driving charge. Even if the calibration results are less than what we had hoped for, it may still be helpful to your case. In most scenarios, it is worth the cost to have the tests done by a mechanic. (If your alleged speed is a long ways off from the 20 miles per hour over the speed limit, I may counsel you differently. For example, I did not counsel my client who was going 112 mph in a 55 mph zone to get a calibration done.) Please call me and we can discuss whether or not it is worth your expense to get a calibration done by a mechanic.
It is important to note that if your speedometer is off in the wrong direction, it may hurt your case, for example if it shows that you thought you were going 80 mph when you were actually going 77 mph. There may be rare circumstances where it might be appropriate to admit evidence of that sort into court. For example, perhaps you knew your speedometer was off or that the speedometer was stuck, and you did not rely on your speedometer to determine your vehicle’s speed. However, in most instances, I would not present “harmful” evidence of that sort. We don’t have to use evidence in court that is not helpful to us.