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.
(..) - We mean you no harm. Where are all the men? Gone. You got nothing to drink? You have traveled far, carried a great burden. I've had worst jobs. Anyway, she's not that heavy. You don't know who she is. What do you mean? Who is she? (..)2012 Snow White and the Huntsman