Lowenstein Sandler, New Jersey’s most profitable law firm, has opened a branch in Washington, an expansion made possible by moving three existing partners and hiring four insurance lawyers from Dickstein Shapiro.

The seven-lawyer office will occupy about 15,000 square feet – “room to grow,” chairman Gary Wingens said Friday—at 2200 Pennsylvania Ave. The expansion marks the second major New Jersey-founded firm to foray into the District this year, and the play continues a trend of outside firms grabbing lawyers and business here.