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Are There Established Therapeutic Levels for Prescription Medication?

Interviewer: Is there a therapeutic level that police test for when they test your blood or a threshold for these medications?

Brian: There are therapeutic levels, scientifically declared therapeutic levels. However, the problem is especially when we’re talking about count two, when someone is driving with medication in their system and they are taking it as prescribed.

When we have printed therapeutic levels, whether someone is inside those therapeutic levels or outside of those therapeutic levels that doesn’t necessarily speak to whether someone is taking the medication as prescribed. They are really two different things.

The law does not say that it is legal to drive within therapeutic levels. The law does not say that is a defense to count two DUI, if someone is driving on prescription medications and the prescription medication are being taken within therapeutic levels.

The law says that it is a defense if a person is taking prescription medications and they are taking those medications as prescribed. Therapeutic levels don’t really speak to that.

Therapeutic Levels Cannot Be Used in a Defense  

For example, someone who has been taking medications for years tend to have a build-up of those prescription medications and as time goes on, there is a lessening effect that those prescription medications have on them, so they need to take higher dosages.

If the person has been on the medication for a long time they may show that outside of normal therapeutic levels but they are literally taking the medication as prescribed.

The prosecutor can talk about therapeutic levels, the defense can talk about therapeutic levels, and in reality it has nothing to do with whether the person has taken their medication as prescribed.

There Are State and Federal Lists of Illegal Drugs That Are Considered to Not Affect Driving Ability

Interviewer: Is there a list of common medications that are considered to have no affect on driving or to have an effect on driving?

Brian: There are several lists, one at the state level and one at the federal level, of chemical substances that are considered illegal to use.

Interviewer: They designate between legal and illegal but they don’t designate between having an effect on driving or not having an effect, right?

Brian: Yes, that is correct.

Interviewer: Impair ability, or an impair ability factor, do they assign that to these chemicals?

Brian: They don’t. It’s not like DUI alcohol where they can say if you are above a 0.08 then it is against the law. There is nothing that says that if you are outside a therapeutic level it is against the law. It is simply did it cause impairment or was it present and you were not taking it as prescribed.

The problem with this whole idea is were you taking the medication as prescribed and was it prescribed to you? The problem is the only person who can really testify to that is the person taking the medications.

Can Your Testimony About Your prescription Medication History Help You at Trial?

Unless, for some reason, there is some sort of assistant that is helping the person in taking their prescribed medications. If the only person that can testify to that is the person who is taking the prescribed medications and that person is also the defendant.

Now all of the sudden you get into constitutional issue because the person has a right to remain silent but they are allowed to testify. Do they want to testify? Do they want to evoke their right to remain silent? Should they be punished simply because they evoke their right to remain silent?

There is no one else to testify to whether they are taking the prescription medications as prescribed. Doctors can’t really explain that. You can put on scientists who can say the person was or was not within therapeutic levels.

Again, that doesn’t speak to whether or not the person was taking prescription medications as prescribed. They are the only ones who can testify to that. So in a way it becomes a Catch 22.

By Brian Douglas Sloan

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AZ DUI Defense Lawyer Brian Douglas Sloan
  • 13+ Years SOLELY Focused on DUI Defense
  • Represented 2,600+ DUI Clients
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