Using the result of Navascues, Pironio and Acin [New J. Phys. 10, 073013 (2008)], we show that any causality respecting reversible theory, which is consistent with the non-demolition principle, has no predictions different from those of quantum theory. The non-demolition principle, which was quantified by Leggett and Garg [PRL 54, 857 (1985)], states that physical properties can be observed without irreversible disturbance. Quantum theory has a limit of weak measurements analyzed By Aharonov et. al, where sequential weak values [Mitchison, Jozsa and Popescu, PRA 76, 062105 (2007)] manifest all the conditions of the non-demolition principle. A theory which obeys the nondemolition principle automatically admits a local-hidden-variable description in the macroscopic limit.