The 'burden of proof' is on the plaintiff, since the defendant is presumed innocent until proven guilty. [=the plaintiff must prove that the defendant is guilty]
The 'tax burden' has been falling increasingly on the middle class. [=middle class people have been paying a greater portion of taxes]
For the rest of his life he 'was burdened' with the knowledge that he had done nothing to help them.
(..) and that is why we cannot afford to be divided. No one nation, no matter how large or powerful can defeat such challenges alone. But the burdens of global citizenship continue to bind us together. In this new century, Americans and Europeans alike will be required to do more, not less. (..)2009 Loose Change 9/11: An American Coup