China, Criminal Justice and Evidence

   I'm back, and this time I'm using this post as a sort of awareness raiser about China's legal system, it's going to be a little opinion-y and a little less science-y but hopefully you'll find it interesting enough to read around and form your own opinions.

   Currently China not only convicts 99.9% of its suspects but it also hands out the death sentence more prolifically than every other legal system in the world combined. While this is a shocking statistic the most important question here is why such a high percentage of suspects are convicted. Either China's police force is made up almost entirely of Sherlock level detectives, or, possibly more credibly, there is something at play here that's heavily skewing the system in favour of the prosecution. It has been claimed that wrongful conviction, tat may be responsible for the absurdly high figure, could be due to given orders and sloppy police work. However China hardly stands alone in suffering from this unprofessional conduct within its judicial system. What really makes the difference in my opinion is the massive credibility given to forced confessions (a slight euphemism for torture until they confess), and the fact the police, who are invariably prosecuting, have complete control of the evidence.

     Now eye witness reports are shaky at best, worse when lead by a skilled lawyer, the fact any credibility is given to that extracted by hanging a person upside down and going to town on their stomach with a hammer is something that would have made even the Roman's blush.

   This becomes an un-fightable one-two punch against the defence once you realise that the defence is not entitled to any of the crime scene evidence. The prosecution can pick and choose evidence that supports their case, making an objective approach to understanding what happened at a crime scene impossible.

   Imagine for example that investigators discover a woman dead in her home due to assault with a blunt instrument. They discover blood spatter from repeated attacks suggesting a man roughly the height of the husband, however the spatter suggests left handed swings when the husband was right handed and also that the only blood on the husbands clothes has large fragments of clots in it, so must be from hours after the crime. Now the police can't find another suspect apart from the husband so they build a case against him. They can simply include that blood is concordant with a man his height and the wife's blood was found on his clothes, leaving out the considerable evidence against their case. Obviously this makes defending near impossible.

    Luckily China is beginning to address the issue, due to mounting internal and external pressure on its judicial system. A recent example of this is the case of Nian Bin in which a grocery store owner was accused of murdering his neighbours by poisoning their porridge with rat poison. The police managed to extract a confession from Nian Bin by torture. Nian was convicted and sentenced to death. However in a series of legal battles, with his sister leading the defence with the aid of a former judge, many holes in the prosecutions argument where uncovered. For example, the man who the police claimed had sold Nian the poison not only looked nothing like Nian's description of him but also did not even sell the type of poison the toxicology report claimed had been used. Also while Nian confessed to having laced the kettle used to boil water for porridge with the poison, not everyone who ate the poison fell sick, whereas everyone who ate the squid did.

   Possibly the most damning thing however was that around 11 minutes into the interrogation video the camera angle shifts, and Nian suddenly appears to be on the verge of crying, and immediately begins to confess to murders, where he had been silent and unresponsive before. Logs of the interrogation found by the former judge suggested a 2 hour gap around this time in which the interrogators had tortured Nian, and allegedly threatened to torture his wife.

    While the highly successful defence team, built upon Chinese lawyers who saw the failure of the current judicial system, they only managed to win Nian retrial after retrial. Judges, lawyers and police hate having cases overturned. It reflects very badly on them, and will destroy their reputation as well as make any promotion much more difficult, and as the retrials are usually conducted in the same court the judge and prosecutors are likely to be those involved in the original case. Nian received four death sentences, and may never have been exonerated (making it into the lucky 0.1%) if it weren't for the fact that recently the Chinese legal system has been heavily embarrassed by having to throw out a murder conviction after the supposed victim reappeared alive over a decade later (Zhang Aiquing, 1994), a case in which confession extracted by torture had been pivotal.

   Cases like this had lead to a revision of the Chinese criminal procedure which allowed the defence team to question the police in court as well as call in their own expert witnesses. One of these expert witnesses happened to be a forensic scientist from Hong Kong, who noticed that the spectrometer slides of the victim's blood were in fact all from the same sample, just with different labels. As if this wasn't bad enough, the conclusions of the report had been written before the results came through, showing that the police had likely forged the results to fit their case.

   This lead to one of the first repealed death sentences in the Chinese judicial system not based on supposedly dead people reappearing alive, or on incontrovertible DNA evidence, but rather on good forensic science and a logical argument.

   While some may see this as a depiction of the corruption and failure of the system, I think it can also be seen as cause for hope. It shows that with enough perseverance logic and evidence are starting to have a place in the Chinese courts, and in addition it shows that many of those high up in the Chinese legal system, for example the former Lawyer who aided the defence as well as many lawyers who aided pro bone, are willing to fight against corruption. In fact Shen Deyong, one of china's most senior judges recently called for more respect for the legal system from those within it. In his words:

"It's preferable to release someone wrongfully, than convict someone wrongfully," he said. "If a true criminal is released, heaven will not collapse, but if an unlucky citizen is wrongfully convicted, heaven will fall."

While I'm not sure how much I agree with this I think it's indicative of general movement of those within the Chinese Judicial system in the right direction. It's something that will hopefully lead to a decrease in the illogical and often barbaric nature of many investigations and possibly result in a less bloody court in general. 

Thanks for reading! Until next time, over and out!

Non-Newtonian Fluid Behaviour and Blood Spatter

It's been a while but we're back with the field of blood spatter analysis. This is, in my opinion, one of the most interesting fields, and hopefully you think so too!

Blood typically behaves pretty strangely for a liquid. For a long time blood was considered as only a Newtonian fluid. A Newtonian fluid can be described as one where liquid drops form due to surface tension and can oscillate during flight away from their source. However Non-Newtonian fluids form by virtue of internal cohesion and are extremely stable in flight.

Blood's interesting because it can either act Newtonian or non-Newtonian depending on victim's condition and the type of injury.

Let's start with Newtonian fluids. The principles used to define Newtonian fluids are taken from his Principia, which say: "The resistance that arises from the lack of (viscosity) of the parts of the liquid, other things being equal, is proportional to the velocity with which the parts of the liquid are separated from one another". Newtonian flow is mainly dependant upon a viscosity constant and surface tension, where each is proportional to the rate of flow. As shown by the equation:

tau=mu*(dv/dy)

Tau = shearing or frictional stress per unit area against the walls of the containing vessel or the enveloping air around a drop, this is called a Reynolds number.

Mu = Coefficient of viscosity, it is a constant of proportionality

dv/dy = A linear change in velocity gradient of flow

So a higher Reynolds number means a fluid is more viscous fluid.

Non-Newtonian fluids, however, follow the formula:

tau=kappa*(dv/dy)^n

Where kappa is a constant but not of viscosity, as the viscosity is no longer a constant. While the shear rate (friction) is constant at any given velocity, it changes depending on the flow rate, which now equals a changing velocity gradient: (dv/dy)^n. The change is now exponential, rather than linear. Tau now refers to the Deborah number, rather than the Reynolds number. It is named after the biblical quote from Deborah: “Everything flows before the lord”. This is because non-Newtonian fluids follow the principle that everything flows given enough time.  Non-Newtonian fluids generally flow much more slowly than Newtonian fluids as the shear (friction) against their path of flow is considerably greater (exponential not linear).

Blood normally behaves as a non-Newtonian fluid as its flow is not evenly distributed but is in fact formed of a core of red blood cells, surrounded by a layer of white blood cells, which in turn are surrounded by a platelets scattered through plasma (axial flow). This type of flow is stable when your bloods flowing normally. However when there are high rates of flow, or in stressful situations, the body shifts water into the veins, disrupting the axial flow and converting the blood to a Newtonian fluid. As we now know, Newtonian fluids are less viscous and less stable. Essentially the blood becomes turbulent.

So why are we interested in this in the first place? Well first of all some organs in the body (for example the brain and adrenal glands) receive Newtonian blood all of the time. This means by looking at blood spatter evidence, and the proportion to which it acts as Newtonian or non-Newtonian can locate where the blood spatter pattern comes from.

The most obvious difference in blood spatter patterning is that Newtonian fluid spatters causes small, dense central circle with a fine satellite spatter, whereas non-Newtonian is more likely to project streaks outwards from the central circle.

Anyway, this has all been very maths-y, but hopefully interesting! Over and out, and until next time!