M.Law is not scoring always. It had been my subject. I myself got 49 marks in 2011 but later I replaced it. I know so many candidates such as my friends who kept this subject unchanged throughout their attempts but they could not avail good marks. My friend, who did 15 correct MCQs in Ots objective paper, got only 7 marks in 2013's overall paper. Many candidates failed in this paper in 2013.
It is risky subject. You cannot trust risky subjects unless you are master in it. However, it's all your choice.

Remember! Easy subjects do not always fetch you a good marks. These are subjected to the trend of marking policy made by FPSC.