Here is the description of the model:
We live in a resource-constrained world where it is important to consider not just what we want, i.e. the principles of open government data, but also what we are willing to give up to get it. This chart provides a road map for deciding between the many aspects of open government data. […]
The model is expressed in an expandable interactive table.
Regarding legal data, the model covers free online access, openness, identifiers, APIs, and Linked Data.
I believe Josh presented the model at the 2013 House Legislative Data and Transparency Conference.
For more details, please see the model.