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<?xml version="1.0" standalone="yes"?> <Paper uid="H86-1016"> <Title>Hypotheticals as Heuristic Device</Title> <Section position="1" start_page="0" end_page="169" type="abstr"> <SectionTitle> Abstract </SectionTitle> <Paragraph position="0"> In this paper we examine the use of hypotheticals as a heuristic device to assist a case-based reasoner test the strengths, weaknesses, and ramifications of an analysis or argument by exploring and augmenting the space of known cases and indirectly, the attendant spaces of doctrine and argument. Our program, HYPO, works in the task domain of the law, particularly, the area of trade secret protection for software. We describe how HYPO generates a constellation of legally-meaningful hypothetical fact situations (&quot;hypos&quot;) which are &quot;near&quot; a given fact situation. This is done in two steps: analysis of the given situation and then generation of the hypos. We discuss the heuristics HYPO currently uses, which include: (1) make a case weaker or stronger; (2) generate an extreme case; (3) generate a near miss; (4) manipulate a near win; and (5) generate a case on a related &quot;dimension&quot;.</Paragraph> <Paragraph position="1"> I. Introduction HYPO is a program to model reasoning with cases and hypotheticals (&quot;hypos&quot;). The program comprises a means of representing and indexing cases in a Case Knowledge Base (&quot;CKB&quot;), a computational definition of relevance in terms of &quot;dimensions&quot; which capture the utility of a case for making a particular kind of argument, a dimension-based method for comparing cases, and methods for generating hypotheticals to help an arguer formulate an argument, gather relevant facts, and explain his argument. HYPO's domain is legal argument where, as illustrated below with examples of oral arguments before the Supreme Court,-cases and hypotheticals are primary tools.</Paragraph> <Paragraph position="2"> In this paper, we concentrate on HYPO's creation of hypothetical new cases to accomplish such tasks as: (1) test the sensitivity of one's argument to absence or presence of certain facts; (2) locate and explore subspaces of relevant cases in the CKB; (3) augment and &quot;flesh out&quot; sparse areas of the CKB; (4) sample the space of implications of a given argument; (5) formulate refinements and refutations of an argument. Thus, we are using hypotheticais as a heuristic device to explore several &quot;spaces&quot; -- the CKB itself, and the spaces of legal doctrine and argument -- and to acquire new case knowledge. HYPO generates these hypotheticals heuristically using certain well-known general heuristics (e.g., examine extreme cases) as well as HYPO-specific ones (e.g., examine weaker/stronger cases along a HYPO dimension).</Paragraph> <Paragraph position="3"> While HYPO is a program whose primary task domain is legal argument, the lessons learned from HYPO should prove useful for other case-oriented tasks like strategic planning and learning by experimentation. The posing and manipulating of hypotheticals is important in strategic planning where one must examine a proposed plan in light of telling what ifs -- all too often the advocate of a plan only tells of its good points and and a devil's advocate is needed to unmask its weaknesses. In learning, some of the questions concerning how to intelligently select examples as training instances have a large overlap with our concerns here. In case-based systems, one ,cannot afford to wait passively for the &quot;right&quot; case to come along before grappling with a potential problem; one must create cases to reason in anticipation. So too in learning systems, one (i.e., the problem generator) must select or generate cases to drive the learning system. The heuristics we discuss here are the subject of another on-going project of ours on intelligent example selection for rule-learning systems like Buchanan and Fu's RL \[1985\]. Before going into details, we must mention that in the law there is a distinction between &quot;real&quot; and &quot;hypothetical&quot; cases. A real case is a case that has been litigated and decided; a hypo has not (even though it might be a very slight variation of one that has, or foretells of cases in the process of coming to light or just &quot;waiting to happen&quot;) \[Rissland, 1985\]. Real cases are the basis of our Anglo-American legal system which reasons according to the standard of precedent, or stare decisis, which means roughly that like cases should be decided similarly and that one gives support for a legal outcome by citing other similar cases which share the desired conclusion and by distinguishing those that do not \[Levi, 1949\]. Of course, what counts as &quot;similarity&quot; is often up for grabs and one can apply the idea of precedent &quot;loosely&quot; allowing broad matches and interpretations or &quot;strictly&quot; allowing only narrow ones \[Llewellyn, 1930, 1933\]. Legal concepts are &quot;open-textured&quot;, that is, they cannot be defined in a purely logical way with necessary and sufficient conditions \[Hart, 1961; Gardner, 1984\]. Further the meaning of concepts (and rules) changes over time, and, in fact, the law can be viewed as a system which learns (in a LEX-like manner) from the cases presented to it \[Rissland & Collins, 1986\].</Paragraph> <Paragraph position="4"> These observations apply mostly to &quot;common law&quot; systems, like our own, which reason in a case-based manner. Others, such as the Continental systems (e.g., German or French) rely mostly on rules and to a much lesser degree on cases. However, even in the most rule-like legal orientations, like statute law, one must rely on cases since rarely is a statute so well-defined as to leave no room for ambiguity or interpretation \[Levi, 1949\].</Paragraph> <Paragraph position="5"> Note, there are two situations where hypotheticals may actually be preferred over real cases: (1) law school teaching; and (2) aspects of litigation. In law school, hypos are used (sometimes unmercifully) to ferret out unspoken assumptions and prejudices of students, to focus attention on subtle or troublesome points, and to exercise the student's argumentative powers \[Gewirtz, 1981; Rissland, 1984\]. In litigation, hypos are used primarily at two points: (a) preparation and &quot;debugging&quot; of an argument in the way a strategic planner &quot;dry runs&quot; his plan, and (b) in oral argument, in oral argument, the hypos usually come from the judges trying to probe an advocate's position and the ramifications of it; once in a while, when a hypo is particularly strong or compelling an advocate might recite a hypo in support of his position, or he might present a &quot;counter-example&quot; hypo to refute or limit his opponent's position \[Prettyman, 1975; Rissland, in press\].</Paragraph> <Paragraph position="6"> Our model of legal reasoning is based on actual verbatim data from experts, namely the Justices of the United States Supreme Court, on legal jurisprudential scholarship, and on scholarly analysis in legal journals. We have also gathered and analyzed interchanges from law school classes (at Harvard Law School) \[Rissland, 1983\], and interviews with a few of our own experts on software trade secret law \[Werner, Ashley & Stucky, 1986\].</Paragraph> <Paragraph position="7"> 2. Examples from Supreme Court Oral Arguments The uses that attorneys and judges make of cases and hypotheticals as tools in argument are illustrated in the oral arguments before the United States Supreme Court. To the chagrin of counsel before the bar of the Supreme Court, the Justices frequently interrupt an attorney's presentation to pose hypotheticals. For example, in Lynch v. Donnelly, 104 S. Ct. 1355 (1984), a case involving the constitutionality of a Christmas creche display of a city on municipal land, the Justices posed the following hypotheticals: To the attorney for the City: Q: Do you think ... that a city should display a nativity scene alone without other displays such as Santa Claus and Christmas trees...? Q: \[C\]ould the city display a cross for the celebration of Easter, under your view? To the attorney opposing the display: Q: \[S\]supposing the creche were just one ornament on the Christmas tree and you could hardly see it unless you looked very closely, would that be illegal? Q: What if they had three wiseman and a star in one exhibit, say? Would that be enough? ... What if you had an exhibit that had not the creche itself, but just three camels out in the desert and a star up in the sky? Q: Well, the city could not display religious paintings or artifacts in its museum under your theory.</Paragraph> <Paragraph position="8"> Q: There is nothing self-explanatory about a creche to somebody ... who has never been exposed to the Christian religion.</Paragraph> <Paragraph position="9"> .Q: Would the display up on the frieze in this courtroom of the Ten Commandments be unconstitutional then, in your view? Q: Several years ago ... there was a ceremony held on the Mall, which is federal property of course .... \[T\]here were 200,000 or 300,000 people ... and the ceremony was presided over by Pope John Paul II. Would you say that was a step, towards an establishment of religion violative of the religion clauses? ... Then you think it would be alright to put a creche over on the Mall? ... How do you distinguish a high mass from a creche? ... \[T\]here was a considerable involvement of government in that ceremony, hundreds of extra policeman on duty, streets closed... That was a considerable governmental involvement, was it not? SUP, Lynch v. Donnelly, Case No. 82-1256, Fiche No. 5 In the above questions, one can see the Justices modifying the fact situation along various dimensions: location, size, and focus of display religious content of the display, nature of the viewer, degree of government involvement Sometimes the purpose of the modifications (and thus the derivative hypos) is to compare the fact situation to actual cases previously decided by the Court to test whether the current case presents stronger or weaker facts. 2 Or a hypothetical case, like the Mall example, may be significant because it did not give rise to litigation.</Paragraph> <Paragraph position="10"> Frequently, the Justices use hypotheticals to apply pressure to the rule proposed by an attorney for deciding the case. That can be seen in the Mall example above and in the following example from New Jersey v. T.L.O, 105 S.Ct. 733 (1985), a case involving the consitutionality of a high school principal's search of a female student's handbag for cigarettes after a teacher reported that she had been smoking in the girls' room. A Justice asked: Q: Do you think then that a male teacher could conduct a pat-down search of a young women at age sixteen to find the cigarettes? In response, the attorney for the state took the position that the Fourth Amendment, which 2See e.g., Stone v. Graham, 449 U.S. 39 (1980): Posting copies of Ten Commandments in schools held unconstitutional; Gilfillan v. City of Philadelphia, 637 F. 2d 924 (CA3, 1980): City-financed platform and cross used by Pope John Paul II to celebrate public mass held unconstitutional; McCreary v. Stone, 575 F.Supp. Ill2 (SDNY 1983): Not unconstitutional for village not to refuse permit to private group to erect creche in public park. prohibits unreasonable searches by law enforcement authorities, does not apply to high school administrators. The Justice rejoined: Q: And does that mean that their authority then to make searches, if the Fourth Amendment is completely inapplicable, extends to any kind of search, strip search or otherwise? SUP, New Jersey v. T.L.O, 1984 Term, Fiche No. 5 In this T.L.O. example, the Justices have posed a short but typical &quot;slippery slope&quot; sequence of hypos, where each hypo is successively more extreme than its predecessor, and the culminating &quot;reductio&quot; case (of strip search) is dearly undesireable and suggests refutation of the attorney's position.</Paragraph> <Paragraph position="11"> Another slippery slope -- this time involving the numerical range of a variable -- can be seen in the following exchange from oral argument from Sony Corp. v. Universal City Studios, 464 U.S. 417 (1984). The attorney was advocating the position that if Sony sold video recorders while knowing that consumers would use them to copy copyrighted materials, then Sony should be legally responsible to the owners of the copyrights: Q: Suppose ... that about 10 percent of all programming could be copied without interference by the producer or whoever owned the program...</Paragraph> <Paragraph position="12"> A: \[ don't think that would make any difference. ! think 10% is too small of an amount.</Paragraph> <Paragraph position="13"> Q: Well, what about 50? The attorney then asserted even if there were only one television program that was copyrighted, if Sony knew the program would be copied, it should be legally responsible. Finally, the Justice asked: Q: Under your test, supposing somebody tells the Xerox people that there are people who are making illegal copies with their machine and they know it .... Xerox is a contributory infringer? A: To be consistent, Your Honor, I'd have to say yes.</Paragraph> <Paragraph position="14"> Q: A rather extreme position.</Paragraph> <Paragraph position="15"> SUP, Sony Corp v. Universal City Studios, Case No. 81-1687, Fiche No. 2 In these last two questions, although the altered fact situations posed by the Justice are still covered by the proposed rule, it is progressively harder for the attorney to justify his position because the hypotheticals present progressively weaker facts; the Justice has &quot;stacked&quot; the hypothetical with extreme facts. The attorney to keep his argument alive must distinguish the current Sony situation and the hypos, indeed, the attorney failed. The Court held for Sony on the ground that the Betamax was capable of substantial noninfringing use because so many programs were not subject to copyright restrictions, 464 U.S. 417, 456.</Paragraph> <Paragraph position="16"> To summarize, the above example illustrate how cases, especially hypotheticals, are used: To present, support and attack positions (e.g., by testing the consequences of a tentative conclusion, pressing an assertion to its limits, and exploring the meaning of a concept); Such observations translate into our heuristics for using hypotheticals which we discuss after we present some background on the workings of HYPO.</Paragraph> <Paragraph position="17"> 3. Background on HYPO: Some definitions.</Paragraph> <Paragraph position="18"> For the purposes of this research, cases are disputes between parties tried by a court, whose decisions are reported in published opinions. The opinion sets forth the facts of the case, the claims made by one party against the other, and the court's holding. Facts are statements about events associated with the dispute that were proved at trial or which the court assumed to be true. A claim is a recognized kind of complaint for which the courts will grant relief (e.g., breach of contract, negligence, trade secrets misappropriation, copyright infringement). The elements of a claim are generalized statements of what facts must be proven in order to prevail on the claim (e.g., the three elements for the existence of a trade secret: &quot;novelty, secrecy, and value in the trade or business of the putative trade secret owner&quot; \[Gilburne & Johnson, 1982, p. 215\]). The holding is the decision of the court as to the legal effect on each claim of the facts of the case, either in favor of the plaintiff or defendant.</Paragraph> <Paragraph position="19"> In HYPO, cases are represented by a hierarchical cluster of frames (flavor instances) with slots for relevant features (plaintiff, defendant, claim, facts, etc.). Some features are in turn expanded and represented as frames (e.g., plaintiff) \[Rissland, Valcarce, & Ashley, 1984\]. The library of cases is called the Case Knowledge Base (CKB). HYPO's current CKB contains a dozen Or so of the leading cases for trade secret law for software. See the Appendix Table 1 for a partial list of cases and a very brief indication of their content.</Paragraph> <Paragraph position="20"> Besides the CKB and the understanding of the legal domain that this case representation implicitly contains, the other major source of domain-specific legal knowledge is in HYPO's dimensions. Dimensions capture the notion of legal relevance of a cluster of facts to the merits of a claim: that is, for a particular kind of case, what collections of facts represent strengths and weaknesses in a party's position. The short answer is that facts are relevant to a claim if there is a court that decided such a claim in a real case and expressly noted the presence or absence of such facts in its opinion. Examples of dimensions in HYPO's area of software trade secret law are: Secrets-voluntarily-disclosed, Disclosure-subject-to-restriction, Competitive-advantage-gained, Vertical-knowledge.</Paragraph> <Paragraph position="21"> Each dimension has several facets: 1. C1 aims 2. Prerequisites 3. Focal-slots 4. Ranges 5. Direction-to-strengthen-plaintiff 6. Significance 7. Cases-indexed For instance, the prerequisites of the Secrets-voluntarily-disclosed dimension are that two corporations, plaintiff and defendant, compete with respect to a product, plaintiff has confidential product information to which defendant has gained access and plaintiff has made some disclosures of the information to outsiders. The prerequisites are stated in terms of factual predicates, which indicate the presence or absence of a legal fact or attribute (e.g., existence of a product, existence of a non-disclosure agreement). The focal slot of this dimension is the number of disclosees and its range is a non-negative integer. To strengthen the plaintiff's position in a fact situation to which this dimension applies, decrease the number of disclosees; the best case being that with 0 disclosees. The significance of the dimension is that courts have found that the prerequisite facts are a reason for deciding a trade secrets misappropriation claim. This dimension indexes at least two cases in the CKB: Midland-Ross in which the court held for the defendant where the plaintiff disclosed the secret to 100 persons, and Data-General in which the court held for plaintiff where plaintiff disclosed to 6000 persons. Some of the dimensions relevant to this paper are summarized in the Appendix; HYPO knows about 30 dimensions in all (some of the others are described in \[Rissland, Valcarce & Ashley, 1984\]). The dimensions were gleaned from law journal articles describing the state of the (case) law in this a,rea \[Gilburne & Johnson, 1982\].</Paragraph> <Paragraph position="22"> The overall flow of information in HYPO is presented in Figure 1. Particularly of interest to us here is HYPO's CASE-ANALYSIS module. In essence, this module works as a diagnostic engine to determine which dimensions apply to a fact situation. The prerequisites, in effect, define antecedent conditions and a dimension (i.e., a possible reason for deciding a claim in a particular way) is the consequent. To make an analogy with the medical domain and MYCINlike diagnosis, the prerequisite facts are like symptomatic features and the dimensions are like intermediate disease classes. The other modules are described in more detail in \[Ashley and Rissland, 1985\] and in \[Ashley, 1986\].</Paragraph> <Paragraph position="23"> The output of the CASE-ANALYSIS MODULE is the Case-analysis-record which contains: I. applicable factual predicates 2. applicable dimensions 3. near-miss dimensions 4. applicable claims 5. relevant CKB cases 6. conflict examples 7. points-and-responses The case-analysis-record is used by HYPO's ARGUMENT and HYPO-GEN modules. HYPO's argument task is to generate 3-ply arguments, which means given the statement of the current facts, (1) side 1 generates a point which includes citation of supporting cases, in particular the one\[s\] HYPO considers the &quot;best&quot; supporting case, abstracting from it the &quot;rule&quot; of that case, and stating how it applies to the current facts; (2) side 2 generates a response which might include citation of a best opposing case, refutation of side l's point with use of a single hypothetical or slippery slope sequence, re-explanation of side l's best case in a way more in line with side 2's position; and (3) side l's counter-response to side 2's response. For the remainder of the paper, we concentrate on HYPO's ability to generate hypotheticals.</Paragraph> </Section> class="xml-element"></Paper>