N.H. Rev. Stat. Ann. § 265-A:9

The provisions of this subdivision do not limit the introduction of any other competent evidence bearing on the question of whether a person charged with the violation of RSA 265-A:2, I(a), or RSA 265-A:3, I, was under the influence of intoxicating liquor or any controlled drug, prescription drug, over-the-counter drug, or any other chemical substance, natural or synthetic, which impairs a person's ability to drive.