Startup Idea: Mac-Compatible Offline Case Management System

Startup idea to develop a robust case management system made specifically for Mac users. This system would facilitate offline work and allow attorneys in small law firms to store all their documents on the cloud, minimizing local storage usage.

I am an attorney for a start-up law firm that has 3 people. I have yet to find a reasonably priced case management system that is compatible with the mac. Some are fine with a PC and have apps that you can download to the iPhone operating system. I do not want a web-based case management system and want to be able to work offline when necessary.

Ideally I would also want to be able to keep all documents on a cloud rather than taking up storage and memory on my computer. I have googled and asked other firms what systems they use. I use an online program now but can never do offline work.