Commercial, family, workplace or neighbourhood mediation: whatever the subject matter, and whatever model the mediator chooses, there is common ground that never changes. Spain’s Law 5/2012 devotes an entire title to the principles governing mediation (articles 6 to 10), later completed by the common principles in article 9 of Organic Law 1/2025. They are five ideas, and they apply to any process, whatever its subject.
Of those five ideas, two are used as synonyms so often that almost no one notices they aren’t.
Asked about the principles of mediation, most people (including some professionals) would simply answer with these two terms as if they were interchangeable: impartiality and neutrality, two words for the same idea. They are not. And the difference is not an academic nuance: it is probably the point at which a mediation process is most often compromised without anyone noticing.
Equality and impartiality: favouring no one
That both parties take part on equal terms, with the mediator acting to the detriment or benefit of neither. It sounds obvious until it is tested in a real case: when one party holds more power (hierarchical, financial, verbal), the temptation to compensate, to lean slightly toward whoever appears to be at a disadvantage, is genuine and understandable.
This is also, precisely, the most common way of losing impartiality. Almost never through a conscious decision; almost always through carelessness.
Neutrality: not the same as impartiality
Here is the distinction that gives this note its title.
- Impartiality relates to the parties: not taking sides between them.
- Neutrality relates to the outcome: not favouring a particular solution.
They are different things, and you can have one without the other. It is entirely possible to treat both parties with scrupulous equality (listening for the same amount of time, asking the same questions, not interrupting one more than the other) and still wish, silently, that the agreement ends up having a particular content.
That combination — impartial but not neutral — is more common than is admitted, and it demands the greatest vigilance, because it leaves no visible trace: no one could accuse you of bias, and yet the process is no longer entirely the parties’ own.
Neutrality is not passivity either. The mediator does not sit back waiting for the parties to work things out on their own; they actively work to bring the parties closer together. What they do not do is decide which way the solution should lean.
Voluntariness: no one has to be here
It is the first principle and the most cited, but it deserves closer attention because it is easily misunderstood. Voluntariness does not only mean that no one forces you to mediate; it means that no one is obliged to stay.
Neither party has to reach an agreement, or even remain in the process until the end. There may be a prior agreement requiring the parties to attempt mediation in good faith before going to court, and that attempt is indeed enforceable — but the outcome never is. In practice, this changes how each session is conducted: if at some point a party is only there out of inertia or pressure, it is no longer mediation, it is a simulation of mediation.
Confidentiality: the most delicate principle to apply
It covers the entire procedure, including its very existence, and protects everyone who takes part under professional secrecy. No one can be called to testify about what was discussed in a mediation.
It only yields in very narrowly defined cases: an express waiver by the parties, a substantiated criminal order, a risk to someone’s safety… and when it does yield, one rule admits no exception: it must be said beforehand, not afterward. Staying silent and explaining later is not prudence, it is a way of breaking the trust everything else rests on.
Within this same logic lies one of the lesser-known and most important rules of the caucus: what one party says in private never reaches the other without their express authorisation. Not as a courtesy. As a matter of principle.
Good faith and cooperation
Organic Law 1/2025 added these two as a cross-cutting reference for all appropriate dispute resolution methods, not just mediation. They do not replace the previous principles; they run through all of them.
One can scrupulously comply with the letter of voluntariness or confidentiality and still act in bad faith (going through the motions of mediating while already preparing for litigation, for example). The law now names this expressly.
Five principles, a distinction almost no one gets right
And one rule applies to all of them: it is not stating them that makes them difficult, it is upholding them when no one is watching. Mediation does not fail from not knowing its principles. It fails, almost always, from a small lapse at some moment when they seemed not to matter.