I would generally say not to be too 'bias', just evaluative. For all of my legal responses I always had a conclusion like "Thus, police powers have clearly been effective in the areas of ____ and ____ in the criminal investigative process. However, as seen in the cases _____ and _____ [which I had talked about in my response], it is clear that law reform is needed to prevent the abuse of these powers, such as..." etc etc. (I've deleted legal from my brain so I can't help with any actual cases, sorry!)
But just remember to evaluate and ALWAYS talk about potential for law reform.