Victim's blood on defendant's clothing - impact spatter or not?

Let us imagine a court scene.  An alleged murderer is on trial.  The prosecution barrister is arguing that the victim's bloodstains on the defendant's clothes are present because  the defendant subjected the victim to a severe beating.  What can the defendant's barrister come up with to counter this assertion?

 

Clearly, the defence barrister wants an innocent explanation for the bloodstains.  For example, the defendant's clothes became bloodstained while he was trying to put the victim into the recovery position.

 

He may be in luck.  An alternative explanation for the amount and distribution of the blood spatter on the defendant's clothing is that the blood originated from the victim's respiratory system i.e. from breathing, coughing or sneezing through a bloody nose or mouth.  

Experiments have shown that an injured victim can produce 'blood aerosols', even if he or she is breathing shallowly through a single nostril or through narrowed jaws, teeth and lips.

The patterns of blood spatter produced by respired 'blood aerosols' can be confused with impact spattered blood.

Here is a very short video showing impact spatter.

Respired blood spatter evidence was pivotal in the eventual acquittal of Sion Jenkins, who spent six years in prison for the murder of his foster daughter, Billie-Jo.

On 15th February 1997, Billie-Jo, 13, was alone at home painting patio doors while Jenkins and his two daughters went shopping.  They lived in Hastings, E. Sussex, in the south of England.

When they returned from their shopping trip, they found Billie-Jo lying in a pool of blood in the back garden.  She had been attacked with an iron tent peg. 

Sion Jenkins became a suspect after 158 microscopic blood spots were found on his clothing.  He was subsequently charged with Billie-Jo's murder.

At his trial in 1998, he was found guilty and sentenced to life imprisonment.

Jenkins has always maintained his innocence.  His first appeal against conviction, in 1999, was a failure but his second was successful.  In August 2004, his conviction was quashed on the grounds that the verdict was unsafe.  He was ordered to be re-tried.

In fact, Jenkins had two re-trials.  The jury were unable to reach a verdict in either re-trial.  After the second re-trial in 2006, Jenkins was officially declared 'not guilty' of Billie-Jo's murder

It was at the re-trials that the respired blood spatter evidence was presented.  Here is a link to an article explaining this evidence.

Blood Spatter Evidence in Sion Jenkins Case

The case remains unresolved.