"But I included a link!" What constitutes plagiarism?

This week has been very frustrating for English teachers. US Senator Rand Paul has been caught plagiarizing his speeches and now over 1,300 words from his book Government Bullies. If you haven't been following this story check out this video from the Rachel Maddow Show. 

And read this article from Buzzfeed about the plagiarism in his book. 

The thing that is so frustrating about this is that I fight with students about this every single week. I constantly get papers submitted with no effort at correctly citing sources. I can't count how many times I have gotten a paper where the student simply submitted a list of links at the end and thinks that's enough to not be charged with plagiarism. But that simply isn't the case. In the case of Rand Paul, simply including a footnote that the information came from somewhere else isn't enough. The cited information must also be correctly cited in the essay. It has to be clear when words are directly cited, paraphrased, or are original. 

Plagiarism is a serious problem in academia. More and more students are thinking plagiarism is "the easy way out" in spite of the risks. To be caught plagiarizing can cost a student his or her education, a professional his career, or can ruin a politician. Isn't it easier to just do the work in the first place?