Actually, such a right exists in some cases, in particular, if it's found to be a taking. https://www.fas.org/sgp/crs/misc/R42635.pdf https://www.fas.org/sgp/c

Actually, such a right exists in some cases, in particular, if it's found to be a taking. https://www.fas.org/sgp/crs/misc/R42635.pdf https://www.fas.org/sgp/crs/misc/R42635.pdf Additionally, states generally can't impair existing contracts through legislation due to the contracts clause. See https://en.wikipedia.org/wiki/Contract_Clause https://en.wikipedia.org/wiki/Contract_Clause (mainly because i'm too lazy to write it all up here).