Accepted the brief, justifiable emotion

Looking back at that time in 1985, when you accepted the brief, did you see this largely or simply as a legal case rather than as a national tragedy and, in that sense, was that the mistake you made?

Yes, I think so. Because I thought this was one more case which would add a feather to my cap. I mean one is always ambitious at that age. But I found later - but then it's too late, one can't walk out of the case one has already taken up - that it was not a case, it was a tragedy. And in a tragedy, who is right, who is wrong etc., all becomes marred in great deal of justifiable emotion.

Please explain to me the highlighted parts.

Though I know in general "brief" means "to tell something shortly" and "justifiable" means "which has reasons to justify/defend".

Source : http://www.thehindu.com/opinion/interview/article488996.ece