Wednesday, April 27, 2011

More Fashionable Nonsense about Numbers and Probable Cause

Yet another court, seemingly bereft of any knowledge of the various uses of numbers, opines that using numbers to express probable cause necessarily deprives the decision maker of its ability to use "situation sense." See United States v. Ludwig, No. 10-8009 (10th Cir., 2011).

For a different view about numbers and their uses see P.Tillers & J. Gottfried, "United States v. Copeland: A Collateral Attack on the Legal Maxim that Proof Beyond a Reasonable Doubt Is Unquantifiable?," 5 Law, Probability and Risk 135 (Oxford University Press, 2006) and P. Tillers, Trial by Mathematics - Reconsidered, -- Law, Probability and Risk -- (forthcoming 2011).

But the 10th Circuit, having disavowed the appropriateness using numbers to discuss probable cause, proceeds to inform Mr. Ludwig why a 58% "accuracy rate" by a sniffer dog is more than enough to satisfy the probable cause requirement -- this is so, the court says, because "probable cause doesn't require an officer's suspicion about the presence of contraband to be 'more likely true than false.'" But isn't this statement by the court just a number by another name? (Yes, it is.)









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The dynamic evidence page
It's here: the law of evidence on Spindle Law. See also this post and this post.

5 comments:

Unknown said...

But it is true that not all quantitative statements are expressed numerically ... for example, I can say, "This is very heavy" or "He is very tall."

But, but ... it is also true that the statement, "The probability of X can be less than 'more likely than not'" is equivalent to the statement, "The probability of X can be less than .5."

Unknown said...

Have judges ever heard phrases such as "a gambler's gut instincts"?

Why do judges seem to think it is impossible for a person to think, "My hunch is that the chances of rain tomorrow are about one-quarter"? Don't judges ever think and speak this way in their daily lives? If so, do the sonorous pronouncements of the Supreme Court about probable cause, cause them (judges) to abandon their common memories and their common sense?

Unknown said...

Of course, numerically-expressed probabilities can lead to abuses. But so what? Science and law can be abused. Shall we abandon all scientific and legal talk?

Unknown said...

Perhaps judges think: "If police officers, magistrates, etc., try hard enough, they can rid their minds of any thoughts of (numerical) probabilities when they think about probable cause. It's just as easy as forcing oneself not to think of pink elephants. Try it for yourself and you'll see what I mean."

Unknown said...

Commonwealth v. Ferreira, 2011 Mass. LEXIS 977 (Oct. 21, 2011): "The prosecutor also erred in equating proof beyond a reasonable doubt with a numerical percentage of the probability of guilt, in this case, ninety-eight per cent. '[T]o attempt to quantify proof beyond a reasonable doubt changes the nature of the legal concept of "beyond a reasonable doubt," which seeks "abiding conviction" or "moral certainty" rather than statistical probability.' Commonwealth v. Rosa, 422 Mass. 18, 28 (1996). 'The idea of reasonable doubt is not susceptible to quantification; it is inherently qualitative.' Commonwealth v. Sullivan, 20 Mass. App. Ct. 802, 806 (1985). See Commonwealth v. Mack, 423 Mass. 288, 291 (1996) ('the concept of reasonable doubt is not a mathematical one')."