Probability In Determining "Reasonable Doubt"

When a juror in a criminal trial is asked to determine whether or not somebody is guilty "beyond a reasonable doubt," how certain does "beyond a reasonable doubt" amount to mathematically?


What I mean is; if "beyond Any doubt" is equal to being 100% certain, then is "beyond a reasonable doubt" somewhere around 51%? 80%? What?

collectively by 12 persons it should mean certain.

but in the real world nothing is, and even death and taxes are getting to be in doubt.

a better term would be absolutely sure.

hdpm can set us straight.

The law-school phrasing is somewhere in the high-90's. One problem with this, however, is that the test is applied to each element on which the state bears the burden of proof. Therefore, if there are, say, 7 things the state must prove in order to get a conviction, and proves each with 90% certainty, then the overall probability that someone is guilty can be less than 50%.

So in the example you provided, is it supposed to net out at the higher or lower figure, legally speaking?

that is not the way it works in practice however. nor do juries even consider "reasonable doubt." most times they basically just say that they felt he did it or not. or, worse yet they have an agenda which has no relation to the truth.


your mathematical percentages also dont make any sense in a way. the real question is whether it is likely that someone who is found by a jury to be 90% likely to have committed these seven acts is not the person who actually did them. there is a lot of publicity about the cases of innocents that are found guilty but my experience is that virtually everyone who is brought to trial is guilty. they do not merely get to trial on the whim of the prosecutor but based on how likely it is that they can prove each element of a crime. in reality it is more like a 99% certainty that the person on trial is guilty of the crime.


Pat

reasonable doubt = 95%

In the example it nets out at the lower figure, but is supposed to net out at the higher one.


Usually the judge tells the jury that they should find the defendant guilty beyond a reasonable doubt by means of holding the state to the proof of each element of the crime beyond a reasonable doubt. In other words: find him guilty by (say) 95% probability by finding each element true by a 95% probability. There generally isn't a discussion about how these don't necessarily mean the same thing.

This isn't what the research on jury verdicts suggests. Jurors generally do a better job of getting the facts straight than judges because they can deliberate over different perceptions and 6 heads are, as they say, better than one. They also tend to come from more diverse backgrounds, are less politically ambitious and far fewer are former prosecutors.


I agree that this scenario could rarely happen in a criminal case, but consider a complex civil claim where the jury has to find a dozen or so elements to be true by the standard of mere probability. In sharply disputed close cases where liability is found, it probably shouldn't be.

civil liabilty much easier to win...

Is beyond a reasonable doubt spelled out to the juries explicity? That is, in a mathematical formula or structure - or just in words that may be interperted differently by various people?


Is beyond a reasonable doubt- cummulative?


As a simple example, say a murder case, and the State has three elements: they place the suspect at the scene of the crime; they prove he/she owned or had access to and was physically in contact with the murder weapon during the time of the crime; and that there was a motive for the crime, say economic gain.


Can the State be weak on one point but strong on others so that overall there is no "reasonable doubt". In the above example say the state was "ironclad" in elements one and two but somewhat weak on the motive. Does this in a sense "ruin" the state's case.


From what some are saying, it appears that the state must prove every single element beyond a reasonable doubt. If just one link is weak then the whole chain crumbles. Are all links given equal weight? What if one of the links is not that important to the case as a whole?