A contract is a promise the law will enforce. The Contract Clauses of Colorado’s and the US’s Constitutions protect existing contracts from laws that would later impair their performance. Public employees have received retirement benefits from PERA since 1931. Cost of living adjustments (COLA) began in 1969 and have evolved ever since. In 2000, the statutory COLA rate was 3.5%. In 2010, the legislature changed it to 2%. Employees who retired between 2001 and 2010 sued the State for violating the Contracts Clause, claiming a violation of their contractual right to the 3.5% COLA at the time of their retirement. The Court ruled there was no contract right guaranteeing a particular COLA formula because 1) it has changed repeatedly over time and 2) there is no express intent that the 2000 legislature intended to bind the 2010 legislature regarding the COLA formula for pre-2010 retirees.