Urologists have taken a stance against predatory publishers by compiling a 'green list' of reputable journals within the speciality (see urologygreenlist.wordpress.com). Urology researchers are invited to recommend journals that should be included on or removed from the list, and to send supporting evidence that will be judged by an international advisory panel. I strongly encourage all research disciplines to create their own green lists.
Such lists seem less likely to result in litigation and are simple to maintain, unlike the task of blacklisting an ever-increasing number of predatory journals (see also 416; 2017, and and Nature 544, 416; 2017). The absence of a journal from the green list does not necessarily indicate that it is a predatory publication, but I would advise authors to confirm a journal's credentials before submitting a manuscript. Nature 544,
The urologists' green list currently contains 52 bona fide journals (including two owned by Springer Nature, the publishers of Nature). We still need to define the criteria for inclusion more clearly, but factors such as association with a professional society, indexing, quality of the editorial board and history are a good start.