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.
(..) - I’ll keep them distracted until you get there. - Just don’t take too long. Come on. When have I ever let you down? Very well. The burden is on me not to destroy the droids until you arrive. Save your energy. I can’t. Don’t give up, Padmé. Obi-Wan’s been here, hasn’t he? (..)2005 Star Wars: Episode III - Revenge of the Sith