50 ILCS 510/5
A political subdivision shall, unless it has a satisfactory relationship for services with one or more firms, evaluate the firms submitting letters of interest, taking into account qualifications, ability of professional personnel, past record and experience, performance data on file, willingness to meet time requirements, location, workload of the firm, and such other qualifications-based factors as the political subdivision may determine in writing are applicable. The political subdivision may conduct discussions with and require public presentations by firms deemed to be the most qualified regarding their qualifications, approach to the project, and ability to furnish the required services. In no case shall a political subdivision, prior to selecting a firm for negotiation under Section 7, seek formal or informal submission of verbal or written estimates of costs or proposals in terms of dollars, hours required, percentage of construction cost, or any other measure of compensation.
50 ILCS 510/5