Douglas Clark had been a criminal defense attorney in the Scranton area for a decade when the natural gas boom came calling in 2007.

A neighbor asked him to review a gas rights lease for his property in the northeastern corner of Pennsylvania, where energy companies began snapping up such leases in the mid-2000s in hopes of tapping into the Marcellus Shale — a sedimentary rock formation rich in natural gas that covers most of Pennsylvania and parts of New York, Ohio, West Virginia, Kentucky and Tennessee. Clark knew virtually nothing about oil and gas leases, but he wanted to help the neighbor. He spent every evening for the next 2 1/2 months poring over oil and gas leases as he negotiated with the gas company. The lease price offered rose from $100 to $750 per acre. Clark realized he was staring at a potentially profitable new direction for his law practice.