Premise: John Dennis Hastert ( [ ˈhæstərt ] born January 2 , 1942 ) is an American former congressman who served as the 51st Speaker of the United States House of Representatives from 1999 to 2007 , representing from 1987 to 2007 . He is the longest-serving Republican Speaker of the House in history , and one of the highest-ranking politicians in U.S. history to have gone to prison . The Speaker of the House is the presiding officer of the United States House of Representatives . The Constitution does not require that the Speaker be an elected House Representative , though every Speaker so far has been an elected Member of the House .
Hypothesis: Dennis Hastert served as a congressman.
Label: ENTAILMENT