▁Thomas ▁Aqu inas . ▁The ▁School ▁of ▁Sal aman ca ▁made ▁notable ▁contributions ▁during ▁the ▁Renaissance . ▁ ▁Modern ▁natural ▁law ▁theories ▁were ▁greatly ▁developed ▁in ▁the ▁Age ▁of ▁En light en ment , ▁combining ▁insp iration ▁from ▁Roman ▁law ▁with ▁philosoph ies ▁like ▁social ▁contract ▁theory . ▁It ▁was ▁used ▁in ▁challeng ing ▁theory ▁of ▁the ▁divine ▁right ▁of ▁k ings , ▁and ▁became ▁an ▁alternative ▁just ification ▁for ▁the ▁establishment ▁of ▁a ▁social ▁contract , ▁positive ▁law , ▁and ▁government — and ▁thus ▁legal ▁rights — in ▁the ▁form ▁of ▁classical ▁republic an ism . ▁Con vers ely , ▁the ▁concept ▁of ▁natural ▁rights ▁is ▁used ▁by ▁others ▁to ▁challenge ▁the ▁legit im acy ▁of ▁all ▁such ▁establish ments . ▁ ▁In ▁the ▁early ▁dec ades ▁of ▁the ▁ 2 1 st ▁century , ▁the ▁concept ▁of ▁natural ▁law ▁is ▁closely ▁related ▁to ▁the ▁concept ▁of ▁natural ▁rights . ▁Indeed , ▁many ▁philosoph ers , ▁jur ists ▁and ▁sch ol ars ▁use ▁natural ▁law ▁syn onym ously ▁with ▁natural ▁rights ▁( ), ▁or ▁natural ▁justice , ▁though ▁others ▁distinguish ▁between ▁natural ▁law ▁and ▁natural ▁right . ▁ ▁Because ▁of ▁the ▁intersection ▁between ▁natural ▁law ▁and ▁natural ▁rights , ▁natural ▁law ▁has ▁been ▁claimed ▁or ▁attributed ▁as ▁a ▁key ▁component ▁in ▁the ▁Dec laration ▁of ▁Independ ence ▁( 1 7 7 6 ) ▁of ▁the ▁United ▁States , ▁the ▁Dec laration ▁of ▁the ▁Rights ▁of ▁Man ▁and ▁of ▁the ▁Cit izen ▁( 1 7 8 9 ) ▁of ▁France , ▁the ▁Universal