Not to have a leg to stand on
دليلي براي اثبات سخن خود نداشتن
He won't have a leg to stand on unless he can prove that ...
Without evidence, we don't have a leg to stand on.
او دليلي براي اثبات گفته خود نخواهد داشت مگر اينکه بتواند ثابت کند که ...
بدون مدرک ما هيچ دليلي براي اثبات...