By Elizabeth Cooper and Tom Doughty Concessions and rent breaks in law firm office space are going, going—and close to gone, even as a few prominent cities prove the exception to the rule. According to Jones Lang LaSalle’s annual Law Firm Perspective, rents have increased an average of 2.1 percent overall across the 41 U.S. designated “law firm markets” in the last year—up more than 14 percent from 2009. While law firm relocations this year included downsizing by an average 15.2 percent, the legal sector is collectively leasing more space nationwide. Furthermore, law firm lease negotiations now favor landlords in…