Theburden of proof is the task of proving that you are correct, for example when you have accused someone of a crime.
The burden of proof is on the prosecution.
See full dictionary entry for burden
burden of proof in British English
noun
law
the obligation, in criminal cases resting initially on the prosecution, to provide evidence that will convince the court or jury of the truth of one's contention
burden of proof in American English
the obligation to prove what is asserted and in dispute