This article explains it:
The Truth About Spygate: Punishing Success and Promoting Parity
"A September 6, 2006 memo from Ray Anderson, the NFL head of game operations, adds to this. However, the rules don’t support this belief. Anderson’s memo reads, “Videotaping of any type, including but not limited to taping of an opponent’s offensive or defensive signals, is prohibited on the sidelines, in the coaches’ booth, in the locker room, or at any other locations accessible to club staff members during the game.”
Unfortunately, the memo misquotes the rules, and Anderson can’t change the rules. Rule changes must be proposed to and voted on by the teams. The NFL cited the misquoted rules against the Patriots from pages A105-A106 of the league’s
Policy Manual for Member Clubs Volume II: Game Operations 2007 edition.
Miscellaneous Rules and Regulations, Section A. reads, “No video recording devices of any kind are permitted to be in use in the coaches’ booth, on the field, or in the locker room during the game.”
The league also cited a portion of section D against the Patriots. Section D reads, “To ensure the protection of equipment and employees of the teams’ video departments, please follow the guidelines listed for the video shooting booths at your stadium.”
The league quoted the first guideline against the Patriots, “All video shooting locations must be enclosed on all sides with a roof overhead.” The rules never prohibit filming coaches. The sections used against the Patriots only concern camera locations.
Anderson’s memo adds an emphasis on signals, which isn’t in the rules. Also, Anderson says that videotaping is prohibited from “any other locations accessible to club staff members.”
This isn’t in the rules either.
The rule mentions only three spots where teams can’t use video equipment during games—the coaches’ booth, the locker room, and the field. No rule bars teams from recording signals as long as they locate their cameras properly.
Despite this, Goodell and especially the media continue to portray signal taping as the problem when the only real issue is camera location.
Even the location technicality isn’t open and shut. Again, consider the differences between Anderson’s memo and the rules. We’ve already seen that Anderson’s any “location accessible to club staff members” isn’t in the rules.
(And if it were, how would staff film games as required?)
Of the three locations the rules actually mention, Anderson substitutes “sidelines” for “field.”
That’s important.
NFL rules seem to define “the field” as the area between the sidelines and the endlines. By that definition, a camera man standing out of bounds isn’t on the “field,” although the rule would stop teams from using helmet cameras like those which the networks sometimes use.
Also, using the Section D guideline about enclosed locations against the Patriots is disputable. The manual says the locations “ensure the protection of equipment and employees.” It doesn’t require teams to shoot from those locations. It only asks that teams provide them.
Defending himself, Bill Belichick said he interpreted the rules based on Article IX of
The NFL Constitution and By-laws. Among other things, Article IX concerns videotaping. It reads, “Any use by any club at any time, from the start to the finish of any game in which such club is a participant, of any communications or information-gathering equipment, other than Polaroid-type cameras or field telephones, shall be prohibited, including without limitation videotape machines, telephone tapping, or bugging devices, or any other form of electronic devices that might aid a team during the playing of a game.”
This seems to ban all taping, but, as we’ve seen, the league has two pages of rules requiring teams to tape and exchange the recordings.
Isn’t that contradictory?
The NFL reconciles it by interpreting Article IX to mean that teams can film during games, but they can only use the recordings between games, not during them. Belichick applied this interpretation to ground level taping too.
Goodell disagreed.
Goodell’s ruling means he applies the Article IX interpretation to Sections B, C, E, and most of D in the Miscellaneous Rules, but to not Section A and the first guideline in Section D.
In contrast, Belichick applied it consistently."
-So Goodell made up a rule about filming signals that didn't exist, then after a year of people violating his made up rule (including the Jets) Goodell decided to enforce it for the first time. He justified it by cherry picking parts of rules, but ignoring the parts he didn't like.
