Jenner & Block has hired an eight-lawyer group of energy and regulatory lawyers from a Chicago boutique that has shuttered, the firm is expected to announce Tuesday.

The lawyers, led by partners Michael Guerra, Anne Mitchell, Glenn Rippie and John Rooney, formerly practiced at Rippie Rooney & Ratnaswamy.

The hiring further strengthens Jenner & Block's ties to one of its prominent clients, Illinois-based energy company Exelon Corp. The addition of the attorneys, including four partners, two associates and two of counsel, also represents a boon to a growing energy practice at litigation-focused Jenner.

Jenner & Block's energy practice informally launched in 2016 when the firm brought back former partner Randall Mehrberg, who was Exelon Corp. general counsel. The next year, the firm hired former Federal Energy Regulatory Commission Commissioner Suedeen Kelly and former FERC general counsel Max Minzner.

The new hires at Jenner also have deep ties to Exelon.

Guerra was formerly a vice president at Commonwealth Edison Co,, which is owned by Exelon. Rippie has represented Exelon for more than 20 years, according to Anne Pramaggiore, CEO of Exelon Utilities and a former McDermott Will & Emery lawyer. Rippie and Rooney's former firm has worked alongside Jenner & Block lawyers in some Exelon cases. The firms also have paired up in representing other clients, including Nicor Gas, Rooney said.

“I've had experience working with Jenner & Block lawyers, from first-year associates to [former chair] Tony Valukas,” Rippie said. “If we were going to partner on a matter for a client, they were the first group of people I'd recommended. There is a commitment to excellence we have shared.”

Pramaggiore and Thomas O'Neill, Exelon's current general counsel, said in an interview they would continue working with Jenner & Block and its new energy partners on the company's legal matters.

Exelon has also worked with the Rippie group in a program the company devised that pairs the company's longstanding outside counsel with minority-owned law firms to help them break into the cloistered energy regulatory policy, Pramaggiore said.

“Being part of a larger firm will give these wonderful lawyers the ability to mold the next generation and spend some time institutionalizing their working model,” Pramaggiore said. “I think that's really important for our industry and the company.”

Jenner & Block last year won two significant cases on behalf of Exelon involving defenses of so-called “Zero Emissions Credit” programs, which provide funds to energy firms that produce energy without carbon emissions, often in the form of nuclear power. Those victories came in U.S. federal appeals courts, upholding legislation in New York and Illinois.

Mehrberg, the co-chair of Jenner's energy practice, said the addition of the eight lawyers was a sign of the success Jenner & Block's energy practice has had in a relatively short period of time.

“This is just very exciting and a little bit affirming,” he said in an interview. “In our third year, being joined by these lawyers who are widely recognized as top energy lawyers just feels great. We have a critical mass of great lawyers, a critical mass of great clientele. And we have had great success on our matters.”

The associates joining the firm are Hanna Conger and Marjorie Kennedy, while the of counsel are Carmen Fosco and Maris Jager.

Jenner has many other ties to Exelon, a Fortune 100 company. William “Bill” Von Hoene, Exelon's current chief strategy officer, and O'Neill, the Exelon general counsel, are former Jenner partners, so is O'Neill's predecessor, Daryl Bradford, who retired from the energy company in 2016.