In this section, we give a brief overview of the regulation of torts in the Netherlands, and discuss an interesting case: the 'bussluis' case.
2.1 Dutch tort law
In civil law systems, the liability for damages is amongst others related to the notion of a tort, or wrongful act. For instance, if someone clumsily parks his car, thereby damaging another already parked car, he commits a tort against the owner of that car and has to compensate for the damages. In Dutch civil law, the essence of the relation between the liability for damages and a tort is regulated in the articles 6:162 and 6:101 of the civil code.
Art. 6:162.1 of the civil code states that a person who commits an unlawful act toward another which can be imputed to him, must repair the damage which the other person suffers as a consequence thereof. Art. 6:162.2 contains the three forms of unlawful acts in Dutch law: a violation of a right, an act or omission violating a statutory duty, and an act or omission violating a rule of unwritten law pertaining to proper social conduct.
Art. 6:101.1 of the civil code states (in synopsis) that, if the damages are partially caused by a circumstance that can be imputed to the party that suffered the damages, the duty to repair the damages is diminished, relative to the amount of imputability of the party that suffered damages and the party that has the duty to repair the damages.
As a result of the Dutch regulations, there are two steps that determine the duty to compensate damages. First, the general duty to compensate damages is established on the basis of art. 6:162 of the civil code. Second, the relative amount of imputability determines the portion of the damages that have to be compensated for.
2.2 The 'bussluis' case
In the eighties a new phenomenon to regulate traffic in inner cities was introduced. The so-called 'bussluis', which is nowadays well-known, was shortly after its introduction rather unknown. The 'bussluis' is an obstacle in the road that can only be passed without problems by buses. Ordinary cars get stuck in it, or if they nevertheless pass through the 'bussluis' the car is damaged. The latter happened to a cab-driver in the mid eighties who ruined his car by driving into a 'bussluis'. The cab-driver could be blamed, because he was driving a one way street in the wrong direction, and had ignored warning signals.
The Dutch Supreme Court (March 20, 1992) decided that the local authorities were guilty of tort and therefore had to compensate for the damages. Since the Supreme Court in the Netherlands only decides legal matters and not factual matters, the case was referred to a Court of Justice in order to determine the amount of damages that had to be compensated. Rather surprisingly, the Court of Justice of the Hague (September 15, 1994) determined that the amount damages that had to be paid was nil. In their opinion, the damages were caused by the cab-driver's own fault for the full 100%. So although the local authorities were guilty of tort, they did not have to pay for the damages after all.
The arguments the Court used to justify that the amount of damages that had to be compensated was nil, were the following:
The cab-driver had trouble to find his way. This had to be reason for him to drive with exceptional care, and to pay attention to signs and to follow the rules of traffic. Since he did not act as he was supposed to, the cab-driver is to blame. Moreover, he is also to blame because he violated a rule of traffic law.
The Supreme Court decided that in case of violation of a traffic norm the violator has responsibility for the damages, if without the violation the damages would not have arisen. This is even true if the way the damages originated were beyond what one could have expected. Therefore the cab-driver is responsible for the damages.
Without violation there would not have been damages, the cab-driver has guilt, and under the current circumstances the Municipality cannot be held responsible for the damages. Therefore the cab-driver is fully responsible for the damages.
In summary, the unexpected character of the 'bussluis' case was that, although the Municipality had committed a tort against the cab-driver and therefore had the general duty to repair the damages (on the basis of art. 6:162 of the civil code), the thereafter determined portion of the damages to be compensated for (on the basis of art. 6:101) was nil because the damages were fully imputed to the cab-driver.
In the following, the case of the cab-driver is used to illustrate both the verbal and the graphical approach to mediating legal argument.
3. DiaLaw: A Verbal Approach to Legal Argument Mediation
The verbal approach is demonstrated by an example in the dialog game for legal justification DiaLaw [Lodder & Herczog, 1995; Lodder, 1998]. After introducing DiaLaw, a sample dialog based on the 'bussluis' case illustrates the opportunities of the verbal approach for education.
3.1 Introducing DiaLaw
In the AI & Law-community a wide range of dialogical models have been developed [e.g., Gordon, 1993; Loui et al., 1993; Hage, Leenes & Lodder, 1994; Lodder & Herczog, 1995; Farley & Freeman, 1995; Bench-Capon, 1995; Prakken & Sartor, 1996; Kowalski & Toni, 1996; Nitta & Shibasaki, 1997]. These are all formal or software models. The tradition of informal models is longer. Perelman’s rhetorical theory [Perelman and Olbrechts-Tyteca 1958], and Habermas’  consensus theory of truth have influenced most dialogical research. Today’s best-known defenders of dialogical models in law are Aarnio, Alexy and Peczenik, who in the beginning of the eighties [Aarnio, Alexy & Peczenik, 1981] integrated their theories that were developed independently in the seventies. DiaLaw has been developed over the last five years.
DiaLaw is a two-person dialog game, in which both players make moves. The goal of the game is that the proponent convinces the opponent of the correctness of his own assertions, or the incorrectness of the opponent's assertions. In their moves the players express an illocutionary act with a propositional content [Searle, 1969]. The illocutionary act is one of the following four:
1. claim - expresses that a certain proposition is true;
2. question - asks a justification of a proposition claimed by the other;
3. accept - expresses agreement on a proposition claimed by the other;
4. withdraw - retracts a proposition claimed by oneself.
If a player claims a proposition (act 1) the content of that proposition is in principle free. The only restriction is that the dialog rules allow it. For instance, a player is not allowed to claim a proposition if he is committed to the opposite. The acts 2-4 are referring to a previous claim, so the proposition is the one of this previous claim.
The first move of the dialog is always a claim by one of the players. Suppose the player Bert claims that the cab-driver is liable. At that moment Bert starts a dialog.
Ernie can do several things in the second move. He can accept that the cab-driver is liable, ask why the cab-driver is liable (question), or even claim that the cab-driver is not liable at all. In the last case the roles change: now Ernie has the burden of proving that the cab-driver is not liable, so he becomes the proponent and Bert the opponent.
Commitment plays an important role in the dialog. Commitment originates after a proposition is claimed, or after a proposition is accepted. Commitment terminates when a proposition is withdrawn. To avoid that the dialog remains an informal talk, a player needs means to force his opponent to accept a proposition. This is what is called forced commitment, and plays a crucial role in the dialog. It occurs when a player is forced to accept a proposition, due to his commitment to other propositions.
The dialog rules describe formally when a move is allowed, and what the consequences of a move for the commitment of the players are. In the Prolog implementation of the game, the levels are initiated, the commitment is settled, and it is indicated who's turn it is. If a player enters a move (speech act and proposition), the program checks whether the move is allowed. If it is, the dialog continues; if it is not the player gets another change.