Lok Sabha Speaker Sumitra Mahajan Saturday defended her decision to deny the leader of opposition post to the Congress, saying it was based on rules and that the Supreme Court had made no observation against her."The Supreme Court has questioned the centre on the issue of Lokpal's appointment in the absence of leader of opposition and the attorney general will inform the court about the government's stand. It has made no observation against the speaker," she said.The Supreme Court had Friday questioned the central government over the issue of appointing a leader of opposition in Lok Sabha, and said it will give a larger interpretation to the concept of the opposition leader if the government failed to resolve the issue."I have taken the decision afters studying the rules and traditions and after taking experts opinion on the issue. No opposition party has more than 55 (members). Till date, the rule that a party should have a minimum of 10 percent seats in the house has not changed," said Mahajan.The speaker noted that in 1980 and 1984, there was no leader of opposition in the house because no party had the required strength.