henry prakken jurix tutorial krakow 10 december, 2014 formal models of balancing in legal cases (1)

Henry PrakkenJURIX tutorial

Krakow10 December, 2014

Formal Models of Balancing in Legal Cases (1)

General setting Inference by constructing and

comparing arguments and counterarguments

Usually legal arguments apply rules Conflicting rules, exceptions

But some legal domains only have factors pro and con

How to build and compare arguments in such domains?

We should save DNAof all citizens

Saving DNA of all citizens

reduces crime

Reducing crime is good

We should not save DNA of all citizens

Saving DNA of all citizens endangers

privacy

Endangering privacy is bad

Attack on conclusion



reduces crime




privacy


Saving DNA of all citizens but crime does not reduce crime

The UK saved DNA of many citizens but crime did not reduce

Attack on premise …



reduces crime




privacy



Prof. P says that …


… often becomes attack on intermediate conclusion



reduces crime




privacy



Prof. P has political ambitions

People with political ambitions are not objective

Prof. P is not objective Attack

on inference



reduces crime




privacy




does not endanger privacy

People who don’t do wrong have nothing to hide

Indirect defence



reduces crime




privacy






Prof. P is not objective





A B

C D E

Dung

A B

C D E

1. An argument is In iff all arguments that defeat it are Out.2. An argument is Out iff some argument that defeats it is In.

Dung

P.M. Dung, On the acceptability of arguments and its fundamental role in nonmonotonic reasoning, logic programming, and n–person games. Artificial Intelligence, 77:321–357, 1995.

Grounded semantics minimises In labelling Preferred semantics maximises In labelling

11

Justification status of arguments

A is justified if A is In in all labellings A is overruled if A is Out in all labellings A is defensible otherwise

A B

C D E

Example (grounded labelling)

Justified: C and DOverruled: ADefensible: B and E



reduces crime




privacy






Prof. P is not objective





C

A B

E

D

Logics for Defeasible

Argumentation

Chain inferences into arguments Deductive inferences

Premises guarantee conclusion Defeasible inferences

Premises create presumption for conclusion Attack arguments with counterarguments See which attacks result as defeats with

preferences Apply Dung (1995) to arguments + defeat

Modgil & me Pollock

S. Modgil & H. Prakken, The ASPIC+ framework for structured argumentation: a tutorial. Argument & Computation 5 (2014): 31-62

Evaluating arguments

Internal justification: Does each step instantiate an acceptable inference scheme? Deductive or defeasible

External justification: have all its counterarguments been refuted? Are its premises acceptable? For defeasible inferences in the argument: what about attacks on the inference or its conclusion?

Contents Factor-based reasoning

Two-valued factors Preferences from precedents More or less abstract factors Many-valued factors Precedential constraint Preferences from values

Running example factors: misuse of trade secrets

Some factors pro misuse of trade secrets: F2 Bribe-Employee F4 Agreed-Not-To-Disclose F6 Security-Measures F15 Unique-Product F18 Identical-Products F21 Knew-Info-Confidential

Some factors con misuse of trade secrets: F1 Disclosure-In-Negotiations F16 Info-Reverse-Engineerable F23 Waiver-of-Confidentiality F25 Info-Reverse-Engineered

HYPORissland & Ashley 1985-1990

CATOAleven & Ashley1991-1997

Citing precedent Mason v Jack Daniels Distillery (Mason) – undecided.

F1 Disclosure-In-Negotiations (d) F6 Security-Measures (p) F15 Unique-Product (p) F16 Info-Reverse-Engineerable (d) F21 Knew-Info-Confidential (p)

Bryce and Associates v Gladstone (Bryce) – plaintiff F1 Disclosure-In-Negotiations (d) F4 Agreed-Not-To-Disclose (p) F6 Security-Measures (p) F18 Identical-Products (p) F21 Knew-Info-Confidential (p)

Plaintiff cites Bryce because of F6,F21

Distinguishing precedent Mason v Jack Daniels Distillery (Mason) – undecided.


Bryce and Associates v Gladstone (Bryce) – plaintiff F1 Disclosure-In-Negotiations (d) F4 Agreed-Not-To-Disclose (p) F6 Security-Measures (p) F18 Identical-Products (p) F21 Knew-Info-Confidential (p)

Plaintiff cites Bryce because of F6,F21

Defendant distinguishes Bryce because of F4,F18

and F16

Counterexample Mason v Jack Daniels Distillery – undecided.


Robinson v State of New Jersey – defendant. F1 Disclosure-In-Negotiations (d) F10 Secrets-Disclosed-Outsiders (d) F18 Identical-Products (p) F19 No-Security Measures (d) F26 Deception (p)

Defendant cites Robinson because of

F1

Distinguishing counterexample

Mason v Jack Daniels Distillery – undecided. F1 Disclosure-In-Negotiations (d) F6 Security-Measures (p) F15 Unique-Product (p) F16 Info-Reverse-Engineerable (d) F21 Knew-Info-Confidential (p)

Robinson v State of New Jersey – defendant. F1 Disclosure-In-Negotiations (d) F10 Secrets-Disclosed-Outsiders (d) F18 Identical-Products (p) F19 No-Security Measures (d) F26 Deception (p)

Defendant cites Robinson because of

F1

Plaintiff distinguishes Robinson because of

F6,F15,F21 and F10,F19

Plaintiff:I should win because

My case shares pro factors F6 and F21 with Bryce, which was won by plaintiff

Defendant:Unlike the present case, Bryce had

pro factors F4 and F18

Defendant:I should win because my case shares con

factor F1 with Robinson, which was

won by defendant

Defendant:Unlike Bryce, the present case has

con factor F16

Plaintiff:Unlike Robinson, the present case has pro factors F6, F15 and F21

Plaintiff:Unlike the

present case, Robinson had con factors F10 and

F19

Basic scheme for reasoning with two-valued factors

AS2:The Pro-factors of current are PThe Con-factors of current are CP are preferred over CCurrent should be decided Pro

The Pro-factors of current are PThe Con-factors of current are CC are preferred over PCurrent should be decided Con

Preferences from precedents (1)

AS2:The Pro-factors of precedent are PThe Con-factors of precedent are Cprecedent was decided ProP are preferred over C

Limitation 1: the current case will often not exactly match a precedent

A fortiori reasoning with two-valued factors

AS3:P are preferred over CP+ are preferred over C-

P+ = P plus zero or more additional pro-factorsC- = C minus zero or more con factors

Limitation 2: not all differences with a precedent will make a current case stronger

(snapshot of)CATO Factor

Hierarchy

F101: Info Trade Secret (p)

F102: Efforts to maintain secrecy (p)

F104: Info valuable (p)

F4: Agreed not to disclose (p)

F1: Disclosuresin negotiations (d)

F6: Securitymeasures (p)

F15: Unique product (p)

Misuse of Trade Secret (p)

F120: Info legitimatelyobtained elsewhere (d)

Vincent Aleven 1991-1997

Distinguishing










Emphasising distinctions










Downplaying distinctions










Exploiting factor hierarchies (1):current misses pro factor

AS4:P1 are preferred over CP2 substitutes P1P2 are preferred over C

Def1:Factor set P2 substitutes factor set P1 iff

For all factors p1 in P1 that are not in P2 there exists a factor p2 in P2 that substitutes p1

Def2:Factor p2 substitutes factor p1 iff

p1 instantiates abstract factor p3 andp2 instantiates abstract factor p3

Example of substitution Precedent – plaintiff

F1 Disclosure-In-Negotiations (d) F4 Agreed-Not-To-Disclose (p) F21 Knew-Info-Confidential (p)

New case – undecided F1 Disclosure-In-Negotiations (d) F6 Security-Measures (p) F21 Knew-Info-Confidential (p)

{F4,F21} > {F1} because of precedent

Plaintiff wants to argue that {F6,F21} > {F1}

Example of substitution (2)

AS2:The Pro-factors of Precedent are {F4,F21}The Con-factors of Precedent are {F1}precedent was decided Pro{F4,F21} are preferred over {F1}

AS4:{F4,F21} are preferred over {F1}{F6,F21} substitutes {F4,F21}{F6,F21} are preferred over {F1}

Example of substitution (3)

AS1:The Pro-factors of Current are {F6,F21}The Con-factors of Current are {F1}{F6,F21} are preferred over {F1}Current should be decided Pro

Current should be decided Pro

The Pro-factors of Current are {F6,F21}

The Con-factors of Current are {F1}

{F6,F21} > {F1}

{F4,F21} > {F1}

{F6,F21} substitutes {F4,F21}

F4 instantiates F102

F6 instantiates

F102

F6 substitutes F4

The Pro-factors of Precedent

are {F4,F21}

The Con-factors of Precedent are {F1}

Precedent was

decided Pro

Distinguishing










Emphasising distinctions










Downplaying distinctions


F102: Efforts to maintain Secrecy (p)








Exploiting factor hierarchies (2):current has additional con factor

AS5:P are preferred over CP cancels C+P are preferred over C+

Def3:Factor set P cancels factor set C iff

For all factors c1 in C+ that are not in C there exists a factor p1 in P such that p1 cancels c1

Def4:Factor p1 cancels factor c1 iff

p1 instantiates abstract factor p2 andc1 is con abstract factor p2 andp1 is preferred over c1

Example of cancellation Precedent – plaintiff

F15 Unique-Product (p) F21 Knew-Info-Confidential (p) F120 Info-Legitimately obtained elsewhere (d)

New case – undecided F1 Disclosure-In-Negotiations (d) F4 Agreed-Not-To-Disclose (p) F15 Unique-Product (p) F21 Knew-Info-Confidential (p) F120 Info-Legitimately obtained elsewhere (d)

{F15,F21} > {F120} because of precedent

Plaintiff wants to argue that {F4,F15,F21} >

{F1,F120}

Example of cancellation (2)

AS2:The Pro-factors of Precedent are {F15,F21}The Con-factors of Precedent are {F120}Precedent was decided Pro{F15,F21} are preferred over {F120}

AS3:{F15,F21} are preferred over {F120}{F4,F15,F21} are preferred over {F120}

Example of cancellation (3)

AS5:{F4,F15,F21} are preferred over {F120}{F4,F15,F21} cancels {F1,F120}{F4,F15,F21} is preferred over {F1,F120}

Def3:{F4,F15,F21} cancels factor set {F1,F120} since F4 cancels F1

Def4:F4 cancels F1 since

F4 instantiates abstract factor F102 andF1 is con abstract factor F102 andF4 is preferred over F1

Current should be decided Pro

The Pro-factors of Current are

{F4,F15,F21}

The Con-factors of Current are {F1,F120}

{F4,F15, F21} > {F1,F120}

{F15,F21} > {F120}

{F4,F15,F21} cancels {F1,F120}

F4 instantiates

F102

F1 is con F102

F4 cancels F1The Pro-factors of Precedent

are {F15,F21}

The Con-factors of Precedent

are {F120}

Precedent was

decided Pro

{F4,F15,F21} > {F120}

F4 > F1

From two-valued to many-valued factors (dimensions)

Dimensions can have a value from an ordered range of values

Numbers Anything else that can be ordered

Notation: (dimension,value) or (d,v) Dimensions have polarities:

con pro

0,1,2,…. .…, 500, …....

Primary school, secondary school, Bsc, Msc, Dr

<

Example dimensions in HYPO

Number of disclosees (0,1,….) Competetive advantage (none, weak,

moderate, strong)

pro con

0 1 2 3 4 5, …....

<

Example dimensions in HYPO

Number of disclosees (0,1,….) Competetive advantage (none, weak,

moderate, strong)

con pro

none weak moderate strong

<

A fortiori reasoning with dimensions

AS6:P1 are preferred over C1P2 are at least as strong as P1C1 are at least as strong as C2P2 are preferred over C2

Def5:Set P2 of dimension-value pairs pro is at least as strong as set P1 of dimension-value pairs pro iff

For all pairs (d,v1) in P1 there exists a pair (d,v2) in P2 such that v1 ≤ v2

Set C1 of dimension-value pairs con is at least as strong as set C2 of dimension-value pairs con iff

For all pairs (d,v2) in C2 there exists a pair (d,v1) in C1 such that v1 ≤ v2

Example with dimensions (1)

Precedent – defendant F1 Disclosure-In-Negotiations (d) F21 Knew-Info-Confidential (p) Fx Competetive-advantage = strong (p) Fy Number of disclosees = 10 (d)

New case – undecided F1 Disclosure-In-Negotiations (d) F21 Knew-Info-Confidential (p) Fx’ Competetive-advantage = moderate (p) Fy Number of disclosees = 10 (d)

{F21, Fx} < {F1,Fy} because of precedent

Defendant wants to argue that {F21, Fx’}

< {F1,Fy}

Example with dimensions (2)

Precedent – defendant F1 Disclosure-In-Negotiations (d) F21 Knew-Info-Confidential (p) Fx Competetive-advantage = strong (p) Fy Number of disclosees = 10 (d)

New case – undecided F1 Disclosure-In-Negotiations (d) F21 Knew-Info-Confidential (p) Fx’ Competetive-advantage = moderate (p) Fy’ Number of disclosees = 6 (d)

{F21, Fx} < {F1,Fy} because of precedent

Defendant wants to argue that {F21, Fx’}

< {F1,Fy’}

What if the previous schemes do not apply?

Which decisions are allowed by a body of precedents? Precedential constraint

Where do preferences then come from?

Precedential constraint:consistency of preferences

A preference relation < on factor sets is consistent if and only if there are no factor sets X and Y such that both X < Y and Y < X.

Precedential constraint:allowed and forced decisions

Let < be determined by: A set S of precedents The preferences derivable from it by

AS2 (preferences from precedent) AS3 (a fortiori for two-valued factors)

Assume < is consistent Then a decision pro in a new case C is:

allowed by S iff adding C with decision pro to S leaves < consistent.

forced iff allowed and adding C with decision con to S makes < inconsistent

Following, distinguishing and overruling precedents

Let Prec have pro factors P and con factors C and decision pro.

Let Curr have pro factors Pcurr such that P is included in Pcurr. Following Prec = deciding Curr pro Distinguishing Prec = deciding Curr con

where deciding Curr either pro or con is allowed

Overruling Prec = deciding Curr con where deciding Curr pro is forced

Example (1) Precedent – plaintiff

F1 Disclosure-In-Negotiations (d) F6 Security-Measures (p) F21 Knew-Info-Confidential (p) F23 Waiver-of-Confidentiality (d)

New Case – undecided F21 Knew-Info-Confidential (p) F23 Waiver-of-Confidentiality (d) F25 Info-Reverse-Engineered (d)

{F6,F21} > {F1,F23}

Pro = {F21} > {F23,F25}

Con = {F21} < {F23,F25}

Both pro and con allowed

Deciding pro follows precedentDeciding con distinguishes precedent

Example (2) Precedent 1 – plaintiff

F1 Disclosure-In-Negotiations (d) F6 Security-Measures (p) F21 Knew-Info-Confidential (p) F23 Waiver-of-Confidentiality (d)

Precedent 2 – defendant F6 Security-Measures (p) F21 Knew-Info-Confidential (p) F25 Info-Reverse-Engineered (d)

New Case – undecided F21 Knew-Info-Confidential (p) F23 Waiver-of-Confidentiality (d) F25 Info-Reverse-Engineered (d)

{F6,F21} > {F1,F23}

{F6,F21} < {F25}

Pro = {F21} > {F23,F25}

Con = {F21} < {F23,F25}

Only con allowed

Deciding pro overrules precedent 2Deciding con follows precedent 2

What if the previous schemes do not apply?

Which decisions are allowed by a body of precedents? Precedential constraint

Where do preferences then come from?

Scheme for reasoning with promoted values

Deciding current pro promotes set of values V1 Deciding current con promotes set of values V2 V1 is preferred over V2Therefore, current should be decided pro

Scheme for inferring value orderings from cases

Deciding precedent pro promotes set of values V1 Deciding precedent con promotes set of values V2precedent was decided pro Therefore, V1 is preferred over V2

From factors to values

case contains factor PDeciding case pro when it contains P promotes value VTherefore, deciding case pro promotes value V

Wild animals example

Pierson v Post: Plaintiff is hunting a fox on open land. Defendant kills the fox.

Keeble v Hickersgill: Plaintiff is a professional hunter. Lures ducks to his pond. Defendant scares the ducks away

Young v Hitchens: Plaintiff is a professional fisherman. Spreads his nets. Defendant gets inside the nets and catches the fish.

Slide by Trevor Bench-Capon

Pierson – defendant NotDefLiv: Defendant not pursuing livelihood (p) NotPlLiv: Plaintiff not pursuing livelihood (d) NotOwnLand: Plaintiff not on own land (d) NotCaught: Plaintiff had not caught animal (d)

Keeble – plaintiff NotDefLiv: Defendant not pursuing livelihood (p) PlLiv: Plaintiff pursuing livelihood (p) OwnLand: Plaintiff on own land (p) NotCaught: Plaintiff had not caught animal (d)

Young – (defendant) DefLiv: Defendant pursuing livelihood (d) PlLiv: Plaintiff pursuing livelihood (p) NotOwnLand: Plaintiff not on own land (d) NotCaught: Plaintiff had not caught animal (d)

Factors in the wild animals cases

Con = {PlLiv} < {NotOwnLand,NotCaught,Def

Liv}

Pro = {PlLiv} > {NotOwnLand,NotCaught,Def

Liv}

{NotDefLiv} < {NotPlLiv,NotOwnLand

, NotCaught}

{NotDefLiv,PlLiv, OwnLand} > {NotCaught}

Pierson – defendant NotDefLiv: Defendant not pursuing livelihood (p) NotPlLiv: Plaintiff not pursuing livelihood (d) NotOwnLand: Plaintiff not on own land (d) NotCaught: Plaintiff had not caught animal (d)

Keeble – plaintiff NotDefLiv: Defendant not pursuing livelihood (p) PlLiv: Plaintiff pursuing livelihood (p) OwnLand: Plaintiff on own land (p) NotCaught: Plaintiff had not caught animal (d)

Young – (defendant) DefLiv: Defendant pursuing livelihood (d) PlLiv: Plaintiff pursuing livelihood (p) NotOwnLand: Plaintiff not on own land (d) NotCaught: Plaintiff had not caught animal (d)

Factors in the wild animals cases

Values Cval: Certainty and avoidance of litigation Eval: Economic benefit for society Pval: respecting Property

From factors to values: Deciding pro when case contains PlLiv promotes Eval Deciding pro when case contains OwnLand promotes Pval Deciding pro when case contains Caught promotes Pval Deciding con when case contains NotCaught promotes Cval Deciding con when case contains DefLiv promotes Eval

Values in the wild animals cases

Pierson – defendant NotDefLiv: Defendant not pursuing livelihood (p) NotPlLiv: Plaintiff not pursuing livelihood (d) NotOwnLand: Plaintiff not on own land (d) NotCaught: Plaintiff had not caught animal (d) Cval

Keeble – plaintiff NotDefLiv: Defendant not pursuing livelihood (p) PlLiv: Plaintiff pursuing livelihood (p) Eval OwnLand: Plaintiff on own land (p) Pval NotCaught: Plaintiff had not caught animal (d) Cval

Young – (defendant) DefLiv: Defendant pursuing livelihood (d) Eval PlLiv: Plaintiff pursuing livelihood (p) Eval NotOwnLand: Plaintiff not on own land (d) NotCaught: Plaintiff had not caught animal (d) Cval

Values in the wild animals cases

{} < {Cval}

{Eval,Pval} > {Cval}

Pro = {Eval} > {Eval,Cval}

Con = {Eval} < {Eval,Cval}

Further refinements Promotion and demotion of values Degrees of promotion or demotion

Absolute or marginal Probability of promotion or

demotion

henry prakken jurix tutorial krakow 10 december, 2014 formal models of balancing in legal cases (1)

Documents

bad saving dna

objective saving dna

uk saved dna

privacy endangering

privacy people

labelling slide

inference slide

premise slide