A Court of Law is slightly different. A Court of Law hopes to recount events of the past in the first-hand present. That is to say, yes those events are in the past, but, they are in the present past if that makes sense. They are not events 2,000 years ago, they are events within a few years of each other, at best 40 years.
The Historic Method knows eyewitness testimony in the form of scriptures is far more reliable, hence, that is why they will prefer them over second hand accounts. However, if all sources point towards one direction then we can conclude one thing. A massive conspiracy, or enough to base a conclusion on.
If you want to discount Second hand sources from your own proof that is fine, but, you would be disregarding much history has to teach us, given that it uses the Historic method which allows Second hand sources.