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Certain long-standing customary rights may come to have similar status to common law, even if unwritten. This applies in particular to rights of way and rights to use areas of land in a particular way. For such a right to be upheld by a court, it must have existed 'since time immemorial', not conflict with statute, and to be assumed to be a right, not granted by someone's permission. 'Time immemorial' is difficult to define, of course, and an arbitrary date of 1189 is often taken as equivalent. However, if a right has been exercised for some decades, and local opinion is that it is ancient, and there is no evidence to the contrary, this may well be close enough to 'time immemorial' to satisfy a court.