Journals should avoid plagiarism
A spectrum of plagiarism (Turnitin) ranges from cloning someone else's entire paper to sampling some pieces with a few word alterations.
Lexis offers plagiarism-checking software via its course software.
UW IT licenses VeriCite for UW instructors to use in Canvas. In May 2018, UW IT told me that the license can't include a student-edited journal. - Mary Whisner, research services librarian.
Online services don't cover everything.
The commercial plagiarism-checking services can save you a lot of work, but nothing is perfect. Bear in mind that an author could have plagiarized from a book or article that's not in the service's database. If you suspect plagiarism, check further, even if the program didn't find a problem.
Watch for dates.
If an author submits a paper that was supposedly just written, watch for sections that cite old sources (e.g., C.F.R. sections or U.S.C.A. pocket parts from a few years ago). That could be a sign that the author "borrowed" someone else's footnotes.