The legal or ultimate burden remains with the plaintiff, but in the absence of evidence to the contrary adduced by the defendant, an inference of causation may be drawn although positive or scientific proof of causation has not been adduced. (macleanpersonalinjury.com)
Economic research on employer payroll taxes finds that their ultimate burden is shifted over several years to employees — via slower growth in wages and salaries. (theglobeandmail.com)
Equally it is not trivial to calculate exactly where the ultimate burden of taxation falls. (politics.stackexchange.com)