Consider a tight-knit community that might be willing to contribute to a communal data set via a website, Facebook group, etc. As a concrete example, let's say that the data set is a list of landmarks.
The goals of the project would be clearly stated, including that the data set will be explicitly licensed as open data.
What are the best-practices (or risks) with this approach? Should contributors be asked to acknowledge a "terms of service" before submitting?
Suppose further that another data set is a list of businesses with operating hours and a contact number. Does that change the complexion of the risks?
Generally speaking, how does one determine what is acceptable in these cases? I'm curious in general but especially vis-a-vis Canada and US law.