Duncan Green Brown & Langeness PC Law Offices | Duncan, Green, Brown & Langeness - full service law firm with offices in Des Moines, Iowa with attorneys and lawyers practicing in areas such as Business and Commercial Matters, Civil Litigation, Construction and Real Esate Law, Employment L DUNCAN, GREEN, BROWN & LANGENESS is a full service law firm with offices in Des Moines, Iowa with attorneys and lawyers practicing in areas such as Business and Commercial Matters, Civil Litigation, Construction and Real Esate Law, Employment Law, Estate Planning and Probate Administration.