Re: corporate resolution
The first point to keep in mind is that whether someone has the authority to bind the organization to a contract depends upon who is asking the question. Suppose the vice president of manufacturing of XYZ Corporation orders $100,000 worth of widgets for use in XYZ's routine production operations. From the standpoint of the seller of the widgets, this vice president probably has authority, and if XYZ tries to evade liability on the contract, it is likely to lose. In this example, the authority flows "ex officio," i.e. XYZ will be bound because its vice-president of manufacturing can reasonably be presumed to hold requisite authority for a deal of this kind. On the other hand, the V-P manufacturing could not be presumed to have authority to sign a merger agreement.
Within XYZ Corporation, however, there may be a board of directors policy that ONLY the V-P of Purchasing may sign contracts for widgets. The V-P Manufacturing may be in big trouble within the company for what he did, but unless the widget supplier had actual notice that the V-P Mfg. lacked authority, the deal holds.
This background is perhaps important to answering your question because of the point-of-view aspect of the "authority" question in general.
Now, the answer to your question. I think the word "hereby" provides the answer. If the person is authorized "hereby," i.e. by virtue of a particular resolution, there is a clear implied message that the authority did not exist before the date of the resolution.
If the resolution merely said "John Doe is authorized to sign contracts." it could establish a new policy, or it could simply declare existing policy. The resolution might have to be interpreted in the light of extrinsic facts and circumstances, such as whether there had been a change in Doe's title or duties, a change in other management policies, the debate at the board meeting prior to adopting the resolution, or anything else that might show what the board intended.
As I indicated earlier, requisite authority to bind an organization may, as respects the rights of outsiders, flow from the office held, prior course of dealings, representations made by the signer, and other factors.
