misrepresentation/undue influence

In the US, there's no uniformity. Some states have posted appellate decisions online, although these collections often don't go back more than about twenty years. You can search by state here.

There are a number of federal appeals court collections that are fairly comprehensive -- here's one.

British high court decisions (since 1996) can be accessed here. I'm not sure if intermediate court decisions are online.

Australian (federal and state) and New Zealand law reports can be found at this extensive site.

Decisions of the European Court of Justice (1997-present) can be found here.