As we have discussed previously, some cases can be very difficult to prosecute because of the assigned examiner. Today, patent practitioners can have a good window into the situation well in advance through the use of examiner statistics, but those do nothing to change the situation in and of themselves.
So what about getting the case re-assigned? It turns out that this is a herculean task and most attempts are an exercise in futility. The mechanism to achieve reassignment generally involves a Petition (typically decided by the Group Director via one of their delegates), and usually requires that the applicant prove some sort of bias or improper behavior by the examiner or supervisor. Further, the Office typically limits relevant facts only to the specific case in which the petition is filed. That means that statistics showing the examiner is unreasonable compared to the average examiner in the art unit is likely to be dismissed as irrelevant (and further may actually help the Office by showing the examiner is not biased against the particular applicant/application - rather the examiner is difficult for every applicant!).
Likewise, arguments that the examiner does not understand the technology, or is being unreasonable in interpreting the prior art, are also typically dismissed. According to the Office, mere differences in opinion or other substantive issues are meant for an appeal to the Board, and are not relevant to showing bias or improper action on the part of the examiner or supervisor.
If the applicant is unhappy with the initial petition decision via the Group Director, the applicant can also request a review via a second petition under 37 CFR 1.181 to exercise supervisory review over the decision of the TC Director. Typically, these second petitions are delegated to the Office of the Deputy Commissioner for Patent Examination Policy. See MPEP § 1002.02(b).
A couple examples show how difficult it can be for an applicant alleging improper conduct by the examiner. Consider serial numbers 13/4 70,696 and 14/619,334. The decisions by the Deputy Commissioner in each case are here and here.
While it is difficult to find cases in which petitions to reassign to a new examiner are successful, they do exist. One example of a successful approach is where an examiner repeatedly re-opens prosecution responsive to multiple appeal briefs over many years. Another example is where an examiner left voicemails with the attorney of record evidencing a clear bias.
However, even when it might be possible to win a petition to obtain a new examiner, be careful what you wish for because you just might get it. There is no guarantee that a new examiner will be better.
So, if you find yourself considering a request for a new examiner, make sure you have assembled your evidence and can make a strong showing of improper examiner action. If not, focus your efforts on finding a way forward with the assigned examiner and supervisor as best as you can.