Well we just had a Senator from Arizona argue on the Senate floor that Planned Parenthood spends 90% of their funding on abortion and when confronted with that lie (it's 3% and none of it federal funding) his office stated that his comment wasn't intended to be a factual statement.
So you're right they can lie as long as it helps their cause and that's why I think the liberals have done their best for America and it's all downhill from here as conservatives persuade the unwashed masses to do what's not in their or the countries best interest to do.