Don't forget people, the tradition of the British Parliamentary system is very clear, the House is the highest court in the land, when the House makes a directive no one can supersede it, not even the Supreme Court. When the government made excuses about why it 'couldn't' hand over the documents, that was just so much bile and nonsense, because the House can order you to do anything regardless of other laws, because in matters of direct orders of the House everything else is superseded. This is one of the reason why such order are rare.
If the opposition allows the Conservative government to once again ignore the law, Harper will become further emboldened until he simply eliminates parliament altogether. And if you don't think it could happen you are just naive.