WASHINGTON - The government should start a criminal investigation into the nation's largest teachers union to see whether the organization improperly used dues money to influence elections, a conservative law firm says. The National Education Association denied any wrongdoing. Landmark Legal Foundation said Thursday it reviewed thousands of pages of NEA records documenting political activities that were not reported to the government — and should have triggered tax payments. The complaints filed with the Internal Revenue Service (news - web sites) and Justice Department (news - web sites) alleged the union spent tens of millions of dollars from member tax-exempt...