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I find this rule to be sort of confusing. Can a lawyer represent a client against a former agency for which he worked if he was personally and substantially involved in specific legislation or rulemaking, insofar as he was not involved in a specific case concerning that issue, or that he was not involved in a specific case concerning that issue in which a party represented at that time now seeks his legal counsel. For instance, say someone works for the EPA and handles chemical dumping cases. If a client who represents an organization that is involved in a dispute with the EPA concerning chemical dumping, does it matter if the lawyer handled a chemical dumping case with that party or does his substantial and personal involvement with the underlying matter of chemical dumping automatically rule him ineligible to take the case?

I hope I explained this okay, thanks!