Over the last week, Sen. Rand Paul (R-Ky.) has been accused of multiple counts of plagiarism -- both in speeches he gave and in a book he wrote.
So what has happened, and what does it mean going forward?
Here's what you need to know.
What is he accused of?
The first accusations of plagiarism came from MSNBC's Rachel Maddow, who noted that Paul recounted the plot of the film "Gattaca" using the same verbiage used on the film's Wikipedia page.
Since then, there have been several other revelations.
1. BuzzFeed's Andrew Kaczynski reported that Paul had also lifted language from Wikipedia while discussing the movie "Stand and Deliver" in a June 2012 speech.
2. Politico's Alexander Burns reported that Paul, in a 2013 response to President Obama's State of the Union address, used language that was exactly the same as a 2011 Associated Press report. And in a speech at Howard University earlier this year, Paul used language similar to the conservative Christian group Focus on the Family while discussing vouchers.
3. Kazcynski reported Saturday that three pages of Paul's recently published book (more than 1,300 words) borrowed heavily from a 2003 study by the conservative Heritage Foundation, along with another example involving the Cato Institute.
How has Paul responded?
Paul hasn't denied that the language was borrowed. Instead, he has argued that he is the victim of "haters" out to destroy his political career.
"The footnote police have really been dogging me for the last week," Paul said on ABC's "This Week" on Sunday. "I will admit that. And I will admit, sometimes we haven’t footnoted things properly."
Paul added: “In some of the other things that are now going to pop up under thousands of things I’ve written, yeah, there are times when they have been sloppy or not correct or we’ve made an error."
But while acknowledging that the cribbing went too far, Paul has also suggested that it wasn't that bad.
Paul has argued that his speeches aren't meant to be meticulously footnoted academic papers. He has also noted that he cited the movies he talked about and, in the case of his book, that the Heritage Foundation study and Cato were cited in the endnotes. Heritage and Cato have both released statements saying they don't take issue with Paul's use of their work.
In other words, Paul has sought to draw a line between sloppiness and dishonesty.
“I take it as an insult and I will not lie down and say people can call me dishonest, misleading or misrepresenting," he said. "I have never intentionally done so.”
So is it plagiarism?
Yes, as long as the language was directly lifted and wasn't quoted.
Despite Paul's insistence that he provided citations, plagiarism is about the words used used as much as the ideas expressed.
So while Paul did indeed cite the movies "Gattaca" and "Stand and Deliver," the issue is more about whether he acknowledged that he was using the exact language that Wikipedia used.
In the case of the Heritage Foundation and Cato, even if the think tanks were cited in the endnotes, that doesn't give Paul license to re-print entire sections of their work without making clear that he has done so.
If a passage is paraphrased in the author’s own words, and footnoted or sourced in an endnote, then it isn’t considered plaigirism. But Paul’s problem is that some passages were used verbatim (or very close to it).
Whether you think plagiarism is a major sin or not, it's pretty clear that this is plagiarism.
How much does it matter?
Plagiarism allegations have touched many politicians, often to little effect. The offenders include President Obama, who during the 2008 presidential campaign appeared to lift language from Massachusetts Gov. Deval Patrick (D). Others accused in recent years include former senator Scott Brown (R-Mass.) and Canadian Prime Minister Stephen Harper.
The one political plagiarism example that everyone cites, of course, is Obama's second-in-command, Vice President Biden. Biden's 1988 presidential campaign was infamously derailed amid multiple allegations of plagiarism, most notably from British Labor Party leader Neil Kinnock.
So if a series of allegations sunk Biden's presidential hopes, what about Paul, who is himself a leading presidential hopeful in 2016?
At this point, it's pretty clear that Biden's sins were much more extensive than Paul's.
Biden lifted Kinnock's precise turns of phrase and his sequences of ideas—a degree of plagiarism that would qualify any student for failure, if not expulsion from school. But the even greater sin was to borrow biographical facts from Kinnock that, although true about Kinnock, didn't apply to Biden. Unlike Kinnock, Biden wasn't the first person in his family history to attend college, as he asserted; nor were his ancestors coal miners, as he claimed when he used Kinnock's words. Once exposed, Biden's campaign team managed to come up with a great-grandfather who had been a mining engineer, but he hardly fit the candidate's description of one who "would come up [from the mines] after 12 hours and play football." At any rate, Biden had delivered his offending remarks with an introduction that clearly implied he had come up with them himself and that they pertained to his own life.
As you can see, Biden was guilty of more than just plagiarism; he apparently appropriated someone else's life story. The plagiarism allegations also fit into a pattern of exaggerations that called into question Biden's character itself.
In Paul's case, the plagiarism -- for now -- appears to be more about sloppiness.
But when it comes to presidential politics, sloppiness can be deadly as well. And given the growing number of examples, it's pretty clear the sloppiness wasn't limited to one or two circumstances.
Paul, we all must remember, is still something of a political outsider, having won just one statewide election. He's a gifted messenger himself, but he's got a largely untested political team around him, and that team's handling of this situation will say a lot about whether it can put up with well-funded and experienced opposition research operations during the 2016 presidential campaign.
"This is a make or break moment," said one GOP consultant allied with the tea party and requested anonymity to discuss the matter candidly.
Paul's plagiarism problems aren't huge news right now. To the extent that they belie a sloppy operation and similar problems that lie ahead, they could matter a great deal.