Pro-Con resources like the ones on this page typically offer a broad overview of a topic, including important laws, events, and people involved in the discussion. They also will present both sides of the issue, highlighting key arguments.
In addition to offering solid summaries of ongoing debates, these are great places to find outside resources. Most often there will be a bibliography following the article, or hyperlinks within the essay itself, either leading to news documents or primary resources.
These are great places to start if you are researching an issue, but be aware of the publication date. They may not reflect the most up-to-date developments related to the discussion.
Opposing Viewpoints is a book series and database which features discussions of social, political, and ethical issues.
You can find many of the print books at the library.