If you want to research a topic, it's a good idea to start with a database. A database is way of finding journal articles (and sometimes other material) on a particular topic or by a particular author.
All databases will give you the bibliographic information (e.g. author, title, journal name) about an article, some will give you an abstract (brief summary) of the article, and some will also give you the full text as well (i.e. the complete article). Useful databases include:
HeinOnline
HeinOnline includes a large collection of full-text journals, mainly in law. This criminal justice and criminology collection in HeinOnline is particularly strong on American and English topics.
Academic Search Complete
A full-text database providing full articles, with their accompanying indexing and abstracts, across a wide range of subjects.
Sage Journals
This database contains journals published by Sage, covering a wide range of subjects within the social sciences, humanities and life sciences.
Westlaw
Westlaw is a law database, and is useful for researching criminal law and the English and Welsh criminal justice system
IBSS - International Bibliography of the Social Sciences
An index to books and journals in the social sciences, including sociology, politics, economics and anthropology.