Complex sentence: The issue of local authority came to a head in February 1949 when the Guam Assembly subpoenaed Abe Goldstein, a U.S. civil service employee of the Navy who allegedly was one of a number of people in violation of a prohibition against Americans owning local businesses.
Split into simpler sentences: The issue of local authority came to a head in February 1949 when Abe Golstein, a civil service employee of the U.S. Navy, was subpoenaed by the Guam Assembly. Goldstein allegedly was one of a number of people in violation of a prohibition against Americans owning local businesses.