Well, that is apparently what happened with Sen. John Walsh, the recently appointed Democratic Senator from Montana, according to The New York Times. Here is more:
...One of the highest-profile credentials of Mr. Walsh’s 33-year military career appears to have been improperly attained. An examination of the final paper required for Mr. Walsh’s master’s degree from the United States Army War College indicates the senator appropriated at least a quarter of his thesis on American Middle East policy from other authors’ works, with no attribution.
Mr. Walsh completed the paper, what the War College calls a “strategy research project,” to earn his degree in 2007, when he was 46. The sources of the material he presents as his own include academic papers, policy journal essays and books that are almost all available online.
Most strikingly, each of the six recommendations Mr. Walsh laid out at the conclusion of his 14-page paper, titled “The Case for Democracy as a Long Term National Strategy,” is taken nearly word-for-word without attribution from a Carnegie Endowment for International Peace document on the same topic.
Sen. Walsh also plagiarized from The Belfer Center for Science and International Affairs, a research institute at Harvard, according to The New York Times.
Think Tank Watch has written about plagiarism at think tanks over the past couple years, and examples can be found here and here.
Although rare, members of Congress plagiarizing from think tanks is not unheard of. Last year, it was reported that Sen. Rand Paul (R-KY) has plagiarized from the Heritage Foundation and Cato Institute.