There may be a legitimate question that the Intoxlyzer 5000 does discriminate against African-Americans. This test is in use throughout much of DoD. It seems at least worth researching and filing a Houser motion in regard to this technology if your client is African-American, and perhaps if the client is a woman. See United States v. Houser, 36 M.J. 392 (C.A.A.F. 1993), which sets out six factors a judge should use to determine the admissibility of expert testimony. In my view, Houser can be used also to challenge the actual "science" underlying testimony for something such as a breath-test machine. In United States v. Griffin, 50 M.J. 278 (C.A.A.F. 1999), the Court of Appeals for the Armed Forces makes specific the application of the Daubert factors under a Houser analysis.
Colin Miller, KKK In A Box?: Connecticut To Replace Controversial Intoxilyzer 5000 With Equally Controversial Alcotest 7110 MKIII-C, EvidenceProf Blog, 15 February 2009.
Prof. Miller's other posts on this subject are at:
Judiciary Under The Influence, Take 3: New Jersey Faces Observation Period Problems With Alcotest, 12 December 2008. According to this piece, there may also be artificially high readings for women.
My favorite text is Lawrence Taylor, Drunk Driving Defense, 6th ed.