What Is Insider-Partial Mediation?
Additional insights into
insider-partial mediation are provided by Beyond Intractability project participants.
Insider-partial mediation is mediation that is done by a person who is already involved in the conflict (i.e. someone who is an "insider"), and, at least to some extent, is aligned with one side or the other (hence, someone who is "partial").  Though this kind of mediator is common in many developing nations, it was first identified in the conflict resolution literature by Lederach and Wehr on the basis of their work in Central America. 
In most cases, insider-partial mediators are people of such high stature that they have credibility with people on all sides of the conflict. The stature of the person mediating is, in fact, the key to the success of insider-partial mediation. This person must be someone who is known and respected by all parties to the conflict and trusted to be fair, even though he or she is associated with one side or another.
The insider-partial mediator's authority stems in large part from a personal relationship** with the disputants. Oscar Arias, former President of Costa Rica, is one well-known example of an insider-partial mediator who helped create the Esquipulas agreement to end the Central American wars in the 1980s.Though Arias was a party to the conflict, his stature as Nobel Laureate and head of a traditionally neutral state made him acceptable as a mediator. 
How Does Insider-Partial Mediation Differ From "Outsider-Neutral" Mediation?
In North America, the mediator is usually expected to be both neutral and impartial. That means that the mediator has no connections to any of the parties and does not overtly favor one side over the other. This "outsider-neutral" conceptualization of mediation suggests that the mediator should come from outside the conflict situation and have no commitment or connection to either side. The mediators' legitimacy and authority depends in part on the fact that they are unbiased and that their lives do not intersect with the lives of the disputants. The outsider-neutral model also emphasizes individualism and egalitarian participation. Disputants are encouraged to solve their own conflicts, with mediators acting as facilitators.  Neutrality and impartiality are typically defined negatively, in terms of what the mediator is not: not biased toward either side; not invested in any particular outcome except settlement; and not expecting any special reward from either side.  In short, mediation is understood as a rather formal activity in which an impartial, neutral third party facilitates direct negotiation.
However, many theorists have pointed out that the complexity of international and intercultural disputes calls for a greater variety of mediator roles. They challenge the assumption that a successful mediator must come from outside the conflict situation. In fact, the image of the detached and rational mediator may not always be appropriate insofar as it fails to take into account the needs and values of many cultures.  For example, in collectivist societies, where it is important to preserve hierarchies, harmony, and trust, face-to-face relations are a usual part of political, economic, and social exchange.  It is in these more traditional cultural settings where insider-partial mediators are more likely to operate. In Central America, for example, people prefer mediators who are involved in the community and hence in the conflict itself.
The insider-partial mediator is typically an interested party who emerges from the system of relationships in which the dispute has occurred. This is someone who is known to be sympathetic to one side but trusted by both sides due to personal distinction or institutional prominence. To describe this trust-based connection, John Paul Lederach speaks of "confianza."  This is a profoundly cultural term, inadequately translated as trust or confidence, which emphasizes relationship building over time. From the perspective of everyday experience in Central America, one does not look to an outside professional when one has a problem with another person. Instead, individuals look for someone whom they trust and whom they know the other party to the dispute also trusts. This kind of person can provide the needed orientation and advice and typically maintains ongoing and enmeshed relationship with the parties. 
Benefits of Insider-Partial Mediation
Though uncommon in North American theory and practice, Lederach, Wehr, and others argue that insider-partial mediators are better in Latin American and non-Western contexts for many reasons. First, insider partial mediators know the situation better, have cultural ties, and are more easily trusted. In many cultural contexts, parties would reject an outsider in favor of someone who knows the history and context of the conflict and the parties. 
While trust is always a concern in selecting a mediator, with insider-partials it is the primary criterion for selection. Because people know each other well and are connected in numerous ways that go beyond the limited service performed,  there is typically close and intimate knowledge shared by the helper and helped. This connection often proves beneficial in reaching a successful settlement. For example, an insider-partial will both discern nuances that an outsider would likely miss, and also better understand the communication preferences of the parties.  In addition, the mediator's personal knowledge of the disputants' histories and the issues at hand is likely to be extremely useful in helping parties to resolve their differences. Finally, because insider-partial mediators are "close to, known by, [and] with and for each side," their presence helps to ensure sincerity and openness throughout mediation. 
Because the insider-partial mediator has close links with the disputants, he or she has a personal interest in a successful outcome and will stick around to make sure any settlement is implemented.  Insider-partials are in this way unlike outsider neutrals, who usually leave to go home or go on to their next case after mediation is done. Not surprisingly, insiders tend to be more invested in the success of the mediation than outsiders, and are more likely to stick around to help resolve any difficulties that develop in the implementation process. This helps to ensure the stability of any settlements reached.
Nevertheless, because they conceive of the ideal mediator as distant and disinterested, many people continue to be wary of the notion of "biased" mediation. In their view, individuals who are partial to one side or the other have no hope of devising a fair solution. Many theorists point out, however, that some degree of bias can actually turn out to be extremely effective in mediation. In part this is because the party that is favored may want to preserve its relationship with the mediator, while the disfavored party may wish to earn the mediator's good will. The mediator thus has benefits to provide to both sides.  Also, a mediator with connections to one or both sides may have the greatest influence in encouraging parties to compromise or change their behavior. Lastly, it turns out that what mediators do in mediation is typically more important than their initial alignment with one side. Mediators can temper their biases to preserve their acceptability to disputants. If, despite their initial closer ties to one side and their personal stake in the outcome, they act in an even-handed manner, they are likely to gain even further trust and influence.
In light of these benefits, Paul Wehr, John Paul Lederach and other scholars have argued that insider-partials are equally or even more legitimate mediators in certain contexts than the typical outside neutrals. Sometimes such mediators work alone, while at other times they team up---one insider-partial working with one outsider-neutral to develop trust among the many parties in a complex, multi-party conflict.