W. Va. Code § 17C-5-5
When a law-enforcement officer has reason to believe a person has committed an offense prohibited by section two of this article or by an ordinance of a municipality of this state which has the same elements as an offense described in said section two of this article, the law-enforcement officer may require such person to submit to a preliminary breath analysis for the purpose of determining such person's blood alcohol content. Such breath analysis must be administered as soon as possible after the law-enforcement officer has a reasonable belief that the person has been driving while under the influence of alcohol, controlled substances or drugs. Any preliminary breath analysis required under this section must be administered with a device and in a manner approved by the department of health for that purpose. The results of a preliminary breath analysis shall be used solely for the purpose of guiding the officer in deciding whether an arrest should be made. When a driver is arrested following a preliminary breath analysis, the tests as hereinafter provided in this article shall be administered in accordance with the provisions thereof.
W. Va. Code § 17C-5-5