How can we ever trust the American mainstream media again?

I don't think the media has been trustworthy for a long time even before the war. Most outlets exist to entertain rather than inform.

If I'm reading you correctly, it's the media's fault we decided to invade Iraq. I'm not sure that's fair. Most of the blame should fall on the Bush Administration. If it deceived the public along the way, that's part of the problem too. There's only so much that the media can do in these circumstances. It would be a little hard to find out from here if Iraq had weapons of mass destruction. Information sources can be limited in times of national security. Besides, there were plenty of people who thought the invasion was a mistake and said so; the government chose to ignore them.

There could be trust of The Mainstream Media again if people were to put such pressure to bear on the desire to include The Human Right To Peace as a right the media had to take notice. The next step would be to introduce The Human Right To Own The Planet into the constituitions of each nation or the equivalents of each constituition. The trouble is if this last were possible The Media would back a propaganda campaign against equality of this sort say that people are evil who want this and any head of state who supports this is either a fool or a mass murder beacause he murdered millions of citizens. These would be the same ones which would push for the right to own the planet. This would work as citizens would accept the idea the leader would kill millions of them if this right were something which could happen.