How Does Radar Work In A Criminal Case?

In this video we’re talking about how a radar gun or radar equipment works in a criminal case.

In most situations people get stopped for speeding or for some sort of a traffic violation. Those are civil charges. But, when they become criminal a whole separate set of rules apply. It’s a whole different ball game.

In Arizona speeding can be criminal. It’s a very common offense. It’s called criminal speeding. Other offenses like reckless driving, racing, exhibition of speed.

These are all criminal offenses and so if an officer used a radar gun in charging that crime we have to make sure that we are looking all of the different potential defenses, all of the different requirements, that an officer needs to meet in order to get that evidence admitted against you.

So, let’s take a quick look and let’s back up and have a brief understanding of how a radar gun or radar equipment works.

So, I have here three different diagrams. We have the radar gun and we have a vehicle. Radar works according to a principle called the doppler effect. You probably know what this is from seventh grade science or you’ve heard it in the real world. It’s that effect that when something is moving and there is a wave in between a point of origin and something that’s moving that wave will differentiate. It will elongate or will condense based upon that movement.

So, in the real world you may have heard this when an ambulance is approaching you or a police car. In this case it may have been a police car.

When a police car is coming up to you and you hear the siren when it’s coming up closer to you you hear it the siren go faster and faster.

You hear wi, wi, wi, wi, wi, wi, wi.

When it passes you you’ll hear that slow down so it’ll go wi, wi, wi, wi, woo, woo, woo, woo, woo as it’s going past you.

That’s because as it’s approaching you the sound wave is condensing. It’s emitting a noise and that sound wave is coming to your ear and the vehicle’s coming closer to you so that sound wave is being compressed.

As it’s leaving you the sound wave is elongating because the origin of that sound is going farther and farther away from you.

And so, that sound is changing the sound, the pitch, the volume is changing as it’s going away from you. Radar works sort of along the same principles, actually, exactly along the same principles.

You have a radar gun and what that does is it emits a wave, it emits a certain frequency kind of like a sound wave. And so, I have that diagram here.

And so, if a vehicle is not moving, if it’s not stationary, I’m sorry if it is stationary and not moving and a radar emits a wave out it’s going to be one particular frequency and we know what that number is because it’s programed, it’s calibrated, or it should be into that radar gun.

And so, it emits a beam. When a vehicle is moving toward the radar gun, so let’s say an officer is parked in the median and a vehicle is passing by that officer and he’s in the proper radar mode and he’s measuring that radar speed when that beam goes out of the radar gun and it bounces off a vehicle and goes back to the gun the frequency that you may have seen here because we know what that is is now going to be condensed because as the vehicle is coming closer to that radar gun it’s going to compress that wave.

Similarly, if a vehicle is going away from the radar gun as you can see in this better diagram here the wave’s going to be elongated by the time it goes back to the radar gun. So, that’s essentially how it works.

Now, in most civil cases that’s enough. That’s all the government needs to prove. They just go into court and they say my radar gun was working, I pointed it, I shot it, it spit out a number or it was in my vehicle or whatever that is that the police go through. But, they don’t really know much about how that works, some of them, some of them do.

But, it’s important to understand that this is what’s happening, all right? So, when it’s a criminal case that sort of standard line that the police have that it just works, they pick it up, they shoot it, it works.

That may work in a civil case, but in a criminal case it’s actually a lot more precise. There’s a lot more work that they need to in order to explain how this works and to make sure that it’s working properly.

So, down here I have a couple of different ways that we can beat radar or we can prevent the radar evidence from coming into court against you. And, I want to review what those are. Number one is the usage.

Did the officer know how to use it? Just like a hammer, you can have a hammer, it can perform a function but if you don’t know how to smash a nail with it or how to break something that you want to do with it it’s an irrelevant tool.

So, if the officer is in the wrong mode or if he’s not using it correctly that’s a big problem. And so, in a criminal case unlike a civil case we have the ability to interview the officer. We can have a full conversation with them, have it recorded and probe whether or not they were using it properly. You can do that in a criminal case. You can also see whether or not that device was properly calibrated, if it’s been properly maintained. Different police agencies have different rules on when they have to maintain and pull equipment out of service in order to calibrate it and put it back into service.

So, we can check those records. We also want to see, once we’ve checked those records, are those records going to be admissible. Meaning can we get that paper document actually into court. It’s called admissibility.

We also want to see whether it’s authentic. Can they prove that the person who was calibrating it, who’s completing that paperwork is it authenticated, it is admissible? Can they get that into court? You can’t just come into court and bring anything you want into court and show it to the judge. You just can’t do that. You have to make sure there’s a proper chain or there’s some sort of an exception in order to get that document that’s outside of court into court.

So, just because you’re being charged with a crime and because the radar may have been working doesn’t mean that the prosecutor or the judge or the defense attorney is going to allow that document to get into court.

Similarly, can the officer articulate any of this stuff? Can the officer talk about the doppler effect or talk about the cone, the width of the cone that the radar gun emits or whether there’s other traffic that the radar beam may have been bouncing back off of instead of your vehicle? Could it have been somebody else’s vehicle? Can an officer articulate any of that? Some of them can, some of them can’t. But, it’s important they do that because this is a criminal case.

This is not something where they can just say, “It just works because.” It’s criminal, they have to prove their elements, all of these elements beyond a reasonable doubt.

Similarly, line of sight, is the officer in a position where he can point the radar gun at something without something else interfering? Can he point it at this vehicle without there being a tree here, or a semi truck, or a series of other vehicles, of other traffic, or is there anything else in the way that could have been problematic and could have interfered with this radar beam?

Also, sometimes we will see the police using wrong equipment numbers.

So, they’ll say that they used equipment A, we’ll get the calibration records for equipment B, and we don’t really know what equipment was used in the actual traffic stop, or who would make these observations.

And so, if you can’t identify that that can be a big problem because now any of the equipment that we have is unreliable.

So, you want to make sure that the numbers all match in order for the equipment to be considered to be reliable and admissible against you. And similarly we want to look at what other evidence is around in a police officer’s case.

So, did the vehicle have dash cam footage? Did the vehicle have GPS data? Does the vehicle have AVL data, automatic vehicle location data? Can we get all of that and if we do does it match everything else? So, if an officer is saying that you’re going 100 miles an hour but he only had to go 95 to catch up to that vehicle, something’s missing there.

Does the GPS data match what the officer’s report says? Many times the police will say that they were seated at one location but the GPS data shows they were across the street. Or they were not in the median at all, they were pulling around doing a u-turn on a bridge. We’re able to get all of that because this is a criminal case, we have a right to review all of that material. And, it’s important that you’re very thorough because a lot of the times these things don’t match. You have to remember these officers, when they’re doing these traffic patrols for criminal speeding or reckless driving or even DUIs a lot of times what they’ll be doing is they’ll be doing multiple stops. Stop after stop after stop after stop for an entire shift. And so, some of their record keeping can be a little bit sloppy or it’s just something that they just forget to document very thoroughly.

And, similarly we want to see sometimes the equipment will be taken out of an officer’s custody. It will be time to go service it.

There will be a problem with it. We have had few occasions where officers have admitted on the stand that they were using equipment that seemed like it was a little bit wonky, like it wasn’t working properly.

And, quite frankly, it’s to their credit that they were so honest about it that they said, “Yes, my equipment was not working properly. “I thought it was working well enough, “that’s why I wrote the ticket. “But, quite frankly, there were some errors in there.” And, sometimes that will only come out during the interviews or during even a trial.

So, some people will come to our office and they’ll say look, “I was cited on radar. “It appears that I was speeding. “I didn’t realize it, it was a mistake. “What can I do, is there anything I can do?” Well, I always like to remind people it’s not our job to disprove anything whether you’re going 100 or 150.

It doesn’t matter. The point is they’ve gotta prove their case, when you come to our office and when you’re charged with a crime you are innocent unless you’ve pled guilty or unless a judge finds you guilty, you 100 innocent.

It’s one of the beauty’s of American law. But, it’s their job to prove all of these elements.

They have to cross that line, they have to meet that burden. Don’t shift that back and put it on us to disprove it. They need to say it was working. They need to say the officer was using it properly. They need to say that they maintained it properly. The government needs to say that this officer knew what he was doing.

And, they need to get that evidence into court against you. And, until they can do all those things you are innocent.

So, if you find yourself in this situation if you want to speak with our team specifically about how any of these principles can apply to your case give our office a call. We offer free case evaluations and we’re happy to sit down with you.

Thanks for watching.

Police use Radar Guns to write traffic tickets all day long – but what about when they use them in criminal cases?

When people are cited for criminal traffic violations, the stipulations on Radar Guns are much different than civil cases. A Radar Gun reading would be considered evidence in a criminal case, and therefore needs to meet certain requirements in order to be admitted against you.

Radar works according to a principle called the Doppler effect. Essentially, the Doppler effect states that waves in between objects will either increase or decrease as they draw closer or farther away from each other. An example of this is when the pitch of a siren changes as an ambulance or police car passes by.
This is because as the vehicle approaches you, the soundwave compresses, and as it drives away from you, the soundwaves elongate. Radar works along the same principle.

Radar Guns emit waves, or frequencies. If the Radar beam is shot toward a stationary object, the wave frequency will be constant. If the beam is shot toward a vehicle that is approaching the Gun, the waves will compress, and if it is shot toward a vehicle that is moving away from the gun, the waves will elongate.
In most civil cases, all that needs to be proven is that a Radar Gun was working properly. The officers do not necessarily need to know how the Radar Gun even works.

In a criminal case, the evidence needs to be a lot more precise.

There are a few defenses that can be used against Radar in a criminal case:

  • Usage

If the officer was using the Radar Gun incorrectly or was in the wrong mode, that will pose a problem in
presenting the Radar reading as evidence in a case.

  • Calibration

If the device used was not properly calibrated or maintained, it will also pose a problem in admitting it as evidence. Different police agencies have different standards on when equipment must be pulled out of service in order to recalibrate or perform maintenance.

  • Admissibility

There is specific documentation that authenticates whether a device has been properly maintained and is admissible in court.

  • Articulate

The accusing officer must be able to articulate the technical means by which the evidence (Radar) was produced. This includes being able to talk about the Doppler effect, the width of the cone that the Radar Gun emits, or whether there is other traffic that the Radar beam may have been bouncing off of. Some officers can articulate these things, others can’t, but it is important that they do if they want their evidence to be admissible in a criminal case.

  • Line of Sight

The officer must be in a position where they can point the Radar Gun at something without something else interfering with it. Trees, traffic, or any other obstructions can’t be in the way of the Radar beam, otherwise, it will be problematic to admit the Radar reading as evidence.

  • Equipment Number

Equipment numbers must match up in order to be admissible as evidence. If the officer claims that they used Equipment A, but only the calibration records are provided for Equipment B, then there will be some confusion as to which equipment was used. If the proper equipment can’t be identified, then it will not be reliable in a criminal case.

  • Service/Work Orders

Sometimes equipment will be taken out of an officer’s custody to be serviced. At times, officers will even admit that the equipment they were using may not have been functioning properly. Other times, this can be proven with service or work order records that suggest the equipment may not have been working properly at the time of the incident.

  • Match Other Evidence

Other evidence, such as dash cam footage, GPS data, automatic vehicle location data, needs to match the Radar data for it to be considered reliable. For example, if an officer alleges that a vehicle was traveling at 100 miles per hour, but they only need to go 95 miles per hour to catch up to the vehicle, that would be inconsistent with what they are alleging.

Something that is important to keep in mind is that it is not upon the defendant of a criminal case to prove anything. It is the accuser that must prove their case. Unless someone has pled guilty or has been found guilty by a judge, they are considered innocent.

In a criminal speeding case, it is up to the State to prove all of the aforementioned elements in order to convict someone who has been charged with criminal speeding.