by Marie C. Baca, Special to ProPublica -- May 19, 2011

A legal tool called forced pooling allows drilling companies to gain access to minerals beneath private property, even if the landowners object. Thirty-eight states have some form of forced pooling law. The specific provisions vary from state to state, but drillers can generally extract minerals from a large area or "pool" -- in most states a minimum of 640 acres -- if leases have been negotiated for a certain percentage of that land. The company can then harvest gas or oil from the entire area. In most cases, drillers aren't allowed to build wells on the unleased land, so they use horizontal wells or other means to collect the minerals beneath those parcels. Related Story: Forced Pooling: When Landowners Can’t Say No to Drilling