That's fast work! The Pistorius case has some interesting contextual features.
You could make reference to the fact that this trial took place in South Africa rather than the UK. Is there any South African lexis? Also, higher class society in South Africa is culturally quite conservative at times. This may be a reason for the quite formal and 'polite' tone.
Purpose and audience are very important. Pistorius knew that his testimony, and demeanor in court, could make the difference between walking free or spending the rest of his life behind bars. He would have been coached on what to say and how to say it by his legal team. One of the key points from the prosecution case was that Pistorius was quite an aggressive, violent and bad-tempered person. Just the sort who would get in a rage and shoot his girlfriend. He had to work hard to present an image in court of being respectful and calm. His language choices would not be natural. Similarly, the defence and prosecution lawyers, with years of experience, would be choosing their language very carefully in order to persuade the judge. Look at emotive terms and connotations of some of the language.
Prosecution and defence also knew that their performance in court was being televised to a world-wide audience. This would affect their language choices too. They had to present an image to the wider audience. The prosecutor, Gerrie Nel, was known as 'The Bulldog' for his tenacity and he would have wanted to maintain this image.
For comparison, have a quick look here
http://miscarriageofjustice.co/index.php?PHPSESSID=31n63djmru1cp3usuonp4434d0&board=22.0At the bottom of the page you can read trial transcripts from a police officer in a high profile UK murder case. (I looked at the Patrol Car Officer testimony) There is still the formal tone, but the witness does not have to worry about going to prison and so their answers are possibly more open. You could also look here
http://www.theguardian.com/media/interactive/2013/oct/16/jimmy-savile-police-interview-transcriptWhich is a police interview but not in a courtroom, where there clearly isn't any attempt to get to the truth. See how the police call him 'Jimmy' and keep repeating 'lovely'...'that's fine'... Not something that you were likely to hear in the Pistorius case!
You could refer to these cases in your coursework, but the focus isn't a comparison, so don't get too distracted.