820 ILCS 90/7
In determining the legitimate business interest of the employer, the totality of the facts and circumstances of the individual case shall be considered. Factors that may be considered in this analysis include, but are not limited to, the employee's exposure to the employer's customer relationships or other employees, the near-permanence of customer relationships, the employee's acquisition, use, or knowledge of confidential information through the employee's employment, the time restrictions, the place restrictions, and the scope of the activity restrictions. No factor carries any more weight than any other, but rather its importance will depend on the specific facts and circumstances of the individual case. Such factors are only non-conclusive aids in determining the employer's legitimate business interest, which in turn is but one component in the 3-prong rule of reason, grounded in the totality of the circumstances. Each situation must be determined on its own particular facts. Reasonableness is gauged not just by some, but by all of the circumstances. The same identical contract and restraint may be reasonable and valid under one set of circumstances and unreasonable and invalid under another set of circumstances.
820 ILCS 90/7