United Parcel Service conceded it couldn’t sue Material Handling Systems for contribution under the Illinois Joint Tortfeasor Contribution Act when Raichid Rafik — a UPS employee who was beaned by a 10-pound metal disc that fell from an overhead package handling system — sued MHS for negligence in designing and installing the warehouse machinery, and UPS for spoliation in failing to preserve the evidence he needed to identify and sue the shipper for negligent packaging. But UPS tried a crossclaim against MHS for …