A federal judge has certified a class action antitrust suit against cable television giant Comcast Corp. that alleges the company set out to establish monopolies in the Philadelphia and Chicago markets and then increase prices once it had eliminated all the competition.

In his 37-page opinion in Behrend v. Comcast Corp., U.S. District Judge John R. Padova certified a class of Comcast subscribers in the 16-county Philadelphia metropolitan area, including six Pennsylvania counties, two Delaware counties and eight New Jersey counties.