Cicero is a web service API that easily integrates into an organization's existing web application or data management software to match any address to its correct legislative districts. Available legislative districts include local council districts in more than 100 cities and state and national districts in the United States, Canada, United Kingdom, New Zealand, and Australia. In addition to geocoding addresses and matching them to the correct legislative districts, Cicero also returns maps of each district and information about each elected official. Cicero also provides non-legislative district matching for census data, counties, school districts, watersheds and police districts.
The Cicero team just released a new dataset - match addresses to the district id's of newly approved, redistricted legislative districts that have not yet taken effect.
On March 19, 2012 they also released a Cicero REST API that supports both XML and JSON data formats.