Problem: An officer suspects that Frank is growing marijuana. Frank lives in a semi-rural area, on a five-acre lot. The officer parks down the street from Frank's house and approaches it on foot. The entire lot is surrounded by a barbed wire fence. "No trespassing signs are attached to the fence every 50 feet. Nonetheless the officer climbs through the fence and approaches Frank's house. There area is heavily wooded lot, and the officer can't see anything until he is within 100 feet of the house, at which point the trees stop and a clearing begins. Hiding behind the last tree, the officer can see a garden plot about 10 feet from the back door to the house. There are tall spiky plants growing in the garden. The officer recognizes the plants as marijuana. At his point has the officer violated the 4th amendment? Can the officer legally approach the house and seize the plants.