A method for modifying design constraints based on observed performance includes measuring a characteristic of a plurality of devices manufactured in a process flow. A design constraint associated with the characteristic is defined. A performance metric relating the performance of the devices as a function of the measured characteristic and the design constraint is generated. The design constraint is modified based on the performance metric. A manufacturing system includes a metrology tool and a design rule monitor. The metrology tool is configured to measure a characteristic of a plurality of devices manufactured in a process flow. The design rule monitor is configured to receive a design constraint associated with the characteristic, generate a performance metric relating the performance of the devices as a function of the measured characteristic and the design constraint, and modify the design constraint based on the performance metric.