In the UK, OPA government customers have each formed an OPA Centre of Excellence and they all share through Cross Government forums. These forums meet at least three times per year and share a variety of OPA related resources including rules, designs, best practices, documentation, standards, learning and rule authors themselves. The organisations have the ability to share rules centrally and work to ensure that rules that produce the same outcome are only ever authored once. This significantly reduces the time taken to build new systems and allows for maximum reuse wherever it is feasible to do so. You can find more information about how to establish a Centre of Excellence here: https://blogs.oracle.com/OPA/entry/building_an_oracle_policy_automation. Hope this is helpful, happy to discuss this further. Matthew
In addition to Matthew's advice on centre's of excellence, here are a couple of other things to think about:
(1) One Government agency can use OPA to deploy a shared decision service for other government agencies or the public at large. For example, a tax agency could set up a web service can answer questions like "what sales tax rate has to be paid on this particular type of good/service?", "what was the list of marginal income tax rates in affect for <tax year>?", "does this person meet the criteria for deferring tax payments?", etc. Or a customs agency could set up a service that answers questions like "for this list of goods in an incoming shipment, what tariff rates apply, and will an inspection or a quarantine period be necessary?".
(2) There are several ways to share rules between agencies - including rule modules (that can be shared with other agencies and incorporated like "shared code"), sharing actual rule documents via source control, or just publishing and sharing entire rule projects for other agencies to use.
With OPA, you can go tactical for a quick-win or strategic for comprehensive long term cross-government cost savings and transparency, or anywhere in between.