In the field of integrated circuit (IC) design it is common to use a plurality of design constraints files to provide the appropriate operational mode when checking the design. Designers typically use the Synopsis® design constraint (SDC) format to describe the constraints in each operational mode. Each time an operational mode is tested a corresponding SDC is used. By merging a plurality of SDCs into a single most pessimistic SDC, designers are able to ensure that the device will properly operate in all the defined operational modes. Only a single run of the merged SDC in the hypothetical mode is required thereby saving time as well as avoiding potential errors from conflicting constraints in different operational modes.