By the way, these are the jury instructions for DUI in California (varies by state). Essentially, this is what the prosecution must prove to obtain a conviction, and for a lawful arrest there must be probable cause that these elements are satisfied:
The defendant is charged [in Count ] with driving under the influence of (an alcoholic beverage/ [or] a drug) [or under the combined influence of an alcoholic beverage and a drug] [in violation of Vehicle Code section 23152(a)].
To prove that the defendant is guilty of this crime, the People must prove that:
1. The defendant drove a vehicle;
AND
2. When (he/she) drove, the defendant was under the influence of (an alcoholic beverage/ [or] a drug) [or under the combined influence of an alcoholic beverage and a drug].
A person is under the influence if, as a result of (drinking [or consuming] an alcoholic beverage/ [and/or] taking a drug), his or her mental or physical abilities are so impaired that he or she is no longer able to drive a vehicle with the caution of a sober person, using ordinary care, under similar circumstances.
The manner in which a person drives is not enough by itself to establish whether the person is or is not under the influence of (an alcoholic beverage/ [or] a drug) [or under the combined influence of an alcoholic beverage and a drug]. However, it is a factor to be considered, in light of all the surrounding circumstances, in deciding whether the person was under the influence.
[In evaluating any test results in this case, you may consider whether or not the person administering the test or the agency maintaining the testing device followed the regulations of the California Department of Health Services.]
[It is not a defense that the defendant was legally entitled to use the drug.]
[If the defendant was under the influence of (an alcoholic beverage/ [and/or] a drug), then it is not a defense that something else also impaired (his/her) ability to drive.]
The statute also creates a rebuttable presumption that the defendant was not under the influence if his or her blood alcohol level was less than 0.05 percent. (People v. Gallardo (1994) 22 Cal.App.4th 489, 496 [27 Cal.Rptr.2d 502].) Depending on the facts of the case, the defendant may be entitled to a pinpoint instruction on this presumption. It is not error to refuse an instruction on this presumption if the prosecution’s theory is that the defendant was under the combined influence of drugs and alcohol. (People v. Andersen (1994) 26 Cal.App.4th 1241, 1250 [32
Cal.Rptr.2d 442].)
Give the bracketed sentence stating that “it is not a defense that something else also impaired (his/her) ability to drive” if there is evidence of an additional source of impairment such as an epileptic seizure, inattention, or falling asleep.
Here's also a jury instruction related to refusal to take a chemical test (NOTE, not refusal to submit to a field sobriety test):
2130. Refusal—Consciousness of Guilt (Veh. Code, § 23612)
The law requires that any driver who has been [lawfully] arrested submit to a chemical test at the request of a peace officer who has reasonable cause to believe that the person arrested was driving under the influence.
If the defendant refused to submit to such a test after a peace officer asked (him/her) to do so and explained the test’s nature to the defendant, then the defendant’s conduct may show that (he/she) was aware of (his/her) guilt. If you conclude that the defendant refused to submit to such a test, it is up to you to decide the meaning and importance of the refusal. However, evidence that the defendant refused to submit to such a test cannot prove guilt by itself.
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Refusal to submit is also an enhancement to DUI:
If you find the defendant guilty of (causing injury while driving under the influence/ [or] [the lesser offense of] driving under the influence), you must then decide whether the People have proved the additional allegation that the defendant willfully refused to (submit to/ [or] complete) a chemical test to determine ((his/her) blood alcohol content/ [or] whether (he/she) had consumed a drug).
To prove this allegation, the People must prove that:
1. A peace officer asked the defendant to submit to a chemical test to determine ((his/her) blood alcohol content/ [or] whether (he/ she) had consumed a drug);
2. The peace officer fully advised the defendant of the requirement
to submit to a test and the consequences of not submitting to a test;
[AND]
3. The defendant willfully refused to (submit to a test/ [or] to complete the test)(./
[AND
4. The peace officer lawfully arrested the defendant and had reasonable cause to believe that defendant was driving a motor vehicle in violation of Vehicle Code section 23140, 23152, or 23153.]
To have fully advised the defendant, the peace officer must have told (him/her) all of the following information:
1. (He/She) may choose a blood(,/ or) breath[, or urine] test; [if (he/she) completes a breath test, (he/she) may also be required to submit to a blood [or urine] test to determine if (he/she) had consumed a drug;] [if only one test is available, (he/she) must complete the test available;] [if (he/she) is not able to complete the test chosen, (he/she) must submit to (the other/another) test;]
2. (He/She) does not have the right to have an attorney present before saying whether (he/she) will submit to a test, before deciding which test to take, or during administration of a test;
3. If (he/she) refuses to submit to a test, the refusal may be used against (him/her) in court;
4. Failure to submit to or complete a test will result in a fine and mandatory imprisonment if (he/she) is convicted of driving under the influence or with a blood alcohol level of 0.08 percent or more;
AND
5. Failure to submit to or complete a test will result in suspension of (his/her) driving privilege for one year or revocation of (his/her) driving privilege for two or three years.
The People have the burden of proving beyond a reasonable doubt that the defendant willfully refused to (submit to/ [or] complete) a chemical test to determine ((his/her) blood alcohol content/ [or] whether (he/she) had consumed a drug). If the People have not met this burden, you must find this allegation has not been proved.