One of our readers recently posted a comment to an Iowa Law Blog entry from last month.  She wants to know who is responsible if someone falls on ice that has accumulated in a parking lot.
Generally, a failed attempt to remove snow and ice can create an artificial condition subjecting the one who created the condition to liability.  Kragel v. Wal-Mart Stores, Inc.  537 N.W.2d 699, 707 (Iowa1995).  A possessor of land, who occupies and controls the land, is subject to liability for physical harm caused to his business customers by a condition on the land if, but only if, the owner:
(a) knows or by the exercise of reasonable care would discover the condition, and should realize that it involves an unreasonable risk of harm to such invitees, and
(b) should expect that they will not discover or realize the danger, or will fail to protect themselves against it, and
(c) fails to exercise reasonable care to protect them against the danger.
Wiedmeyer v. Equitable Life Assur. Society of U.S., 644 N.W.2d 31, 33 (Iowa 2002).
So to answer your question, if the customer has a viable claim for injuries suffered in a slip and fall, the owner of the parking lot is generally liable and must prove that he or she followed the three steps above.  But remember, each case is different, and courts will review a number of factors, including the steps the landowner took to address the snow and ice and the degree of care the plaintiff took in crossing the parking lot.
Be careful out there!