[Code of Federal Regulations]
[Title 36, Volume 1]
[Revised as of July 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 36CFR4.23]

[Page 41]
 
              TITLE 36--PARKS, FORESTS, AND PUBLIC PROPERTY
 
      CHAPTER I--NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR
 
PART 4_VEHICLES AND TRAFFIC SAFETY--Table of Contents
 
Sec.  4.23  Operating under the influence of alcohol or drugs.

    (a) Operating or being in actual physical control of a motor vehicle 
is prohibited while:
    (1) Under the influence of alcohol, or a drug, or drugs, or any 
combination thereof, to a degree that renders the operator incapable of 
safe operation; or
    (2) The alcohol concentration in the operator's blood or breath is 
0.08 grams or more of alcohol per 100 milliliters of blood or 0.08 grams 
or more of alcohol per 210 liters of breath. Provided however, that if 
State law that applies to operating a motor vehicle while under the 
influence of alcohol establishes more restrictive limits of alcohol 
concentration in the operator's blood or breath, those limits supersede 
the limits specified in this paragraph.
    (b) The provisions of paragraph (a) of this section also apply to an 
operator who is or has been legally entitled to use alcohol or another 
drug.
    (c) Tests. (1) At the request or direction of an authorized person 
who has probable cause to believe that an operator of a motor vehicle 
within a park area has violated a provision of paragraph (a) of this 
section, the operator shall submit to one or more tests of the blood, 
breath, saliva or urine for the purpose of determining blood alcohol and 
drug content.
    (2) Refusal by an operator to submit to a test is prohibited and 
proof of refusal may be admissible in any related judicial proceeding.
    (3) Any test or tests for the presence of alcohol and drugs shall be 
determined by and administered at the direction of an authorized person.
    (4) Any test shall be conducted by using accepted scientific methods 
and equipment of proven accuracy and reliability operated by personnel 
certified in its use.
    (d) Presumptive levels. (1) The results of chemical or other 
quantitative tests are intended to supplement the elements of probable 
cause used as the basis for the arrest of an operator charged with a 
violation of paragraph (a)(1) of this section. If the alcohol 
concentration in the operator's blood or breath at the time of testing 
is less than alcohol concentrations specified in paragraph (a)(2) of 
this section, this fact does not give rise to any presumption that the 
operator is or is not under the influence of alcohol.
    (2) The provisions of paragraph (d)(1) of this section are not 
intended to limit the introduction of any other competent evidence 
bearing upon the question of whether the operator, at the time of the 
alleged violation, was under the influence of alcohol, or a drug, or 
drugs, or any combination thereof.

[52 FR 10683, Apr. 2, 1987, as amended at 68 FR 46479, Aug. 6, 2003]