Originally from Take the Witness: Cross-Examination in International Arbitration, 2d Ed.

American lawyers trained in courtroom litigation tend to regard experts – even scientific ones – as about on a par with themselves, which is to say, as paid advocates or “hired guns.”  They have learned that judges and jurors also tend to be skeptical of expert witnesses, and they plan their cross-examinations accordingly. Much time and energy is often spent both in pretrial proceedings and at the trial itself attacking the opposing expert as biased or as not truly expert in the field in which he or she is testifying. 

While all of us could probably point to at least one point in our careers where we have utterly discredited an expert and sent him back to wherever he came from with his tail between his legs (or, at least, so we felt at the time), those tactics are rarely used and even more rarely succeed in international arbitration. International arbitrators generally accept experts as learned and, more importantly, independent, and therefore give them more deference than I, at least, have found appropriate in many circumstances.

To some extent this derives from the civil law tradition where most experts are court-appointed, but even the traditions of common-law jurisdictions outside the United States consider experts as independent of the party hiring them.  Accordingly, a direct attack on a scientific expert is more likely to be considered bad manners that will antagonize the tribunal rather than good trial tactics.  This is not to say that it should never be attempted if you think you really can succeed, but only that you subject any such impulses to considerable second or third thought.