Successfully prove that the expert is not qualified. If he is clearly qualified, do not question him on this point.


Prove that the witness is not honest, sincere or impartial, or that he is biased or prejudiced, or has some interest to gain by testifying. Again, unless you can establish this in a clear-cut manner, leave him or her alone on this point.


Prove that the opinion of the expert is in error. He may be perfectly sincere but, because of a hurried examination or bad instructions from counsel, his opinion is faulty.


Gain admissions which support the testimony of your expert. He might even admit that because reasonable persons differ, the opinion of your expert may have merit.


That the facts he assumed to be correct are not correct or are incomplete. For example, the alleged facts incorporated in a hypothetical question may be incorrect, and if that can be established, he is out on a limb.


If he assumed facts or relied on no facts, then show that the facts are actually contrary to his position.