Hydraulic fracturing – or “fracking” – is a technology designed to release gas or oil bound within shale and other sedimentary formations. It does so by injecting well sites with large volumes of highly pressurized water, sand and chemicals to stimulate and open a target formation using staged horizontal drilling. In contrast to more conventional technology, which targets oil and gas trapped below a sealing caprock, fracking allows operators to boost production from existing formations and to tap into others that were previously considered uneconomical. Published in Environmental Law, Volume XII, No. 2.