Gorton Fisherman said:
So, genuinely curious: where in the NFL rulebook does it grant the commissioner the power to essentially invent new rules out of whole cloth simply by mentioning them in a memo, without any input from or approval by the teams?
This almost requires a separate thread, but bottom line is that no new rules were invented. Direct from the NFL's Bylaws and Constitution, Article IX: Prohibited Conduct, you have:
No member.... shall... Use at any time, from the start to the finish of any game in which a club is a participant, any communications or information gathering equipment, other than Polaroid-type cameras or field telephones, including without limitation videotape machines, telephone tapping or bugging devices, or any other form of electronic device that might aid a team during the playing of a game.
The NFL also releases to its member clubs the
Policy Manual for Member Clubs. This document contains some detailed policies and procedures that are based on the Bylaws and the rule book. Volume 2 of this Manual discusses game operations. In the front of this manual, and in the memo released by the league office, there is a list of changes from previous versions. An example to show the type of detail that would go into this manual, we see the following as a list of changes enacted prior to the 2007 season:
Game Clocks: Added: All clock operators are hired and supervised by the Officiating Department. For playoff games, neutral clock operators will be assigned by the Officiating Department.
These are details that are too fine grained to make it into the Rule Book (which primarily governs playing rules, equipment, etc.) or the Bylaws (which primarily dictates the high-level rules and principles upon which the league will operate).
From the same set of policy changes enacted prior to 2007:
No video recording devices of any kind are permitted to be used in the coaches booth, on the field, or in the locker room during the game
This was the infamous rule clarification that gets everyone hung up when discussing Spygate. While the original rule in the Bylaws does infer that it may be legal to use video recording devices as long as the tape is not used for the same game, the above policy change makes it clear that no video recording devices are allowed on the field, period.
In case you're wondering why the Commissioner gets to make this policy change, consider the following from Article VIII of the NFL's Bylaws:
8.5: The Commissioner shall interpret and from time to time establish policy and procedure in respect to the provisions of the Constitution and Bylaws and any enforcement thereof
TL;DR version: Yes, the Commissioner does have the rights you are asking about. And, no, Belichick did not have the right to ignore the memo from the Commissioner's office. And, yes, Belichick did violate an actual NFL rule when he taped from the sidelines.