Scott Brown and Mitt Romney on July 2. (Jessica Rinaldi/The Boston Globe via Getty Images)

Over the weekend, the campaign of New Hampshire Senate candidate (and former senator) Scott Brown (R) decided to pick a particularly ill-advised fight.

There is a super PAC called Mayday PAC, which has the paradoxical goal of rooting out big money from our political system. To that end, the PAC has endorsed the long-shot candidacy of Jim Rubens, Brown's opponent who has pledged to back campaign finance reform. Rubens is touted on Mayday mail pieces as a "small business owner and entrepreneur." Brown is described as "Former Washington lobbyist and Massachusetts senator."

That's the ill-advised fight Brown decided to pick. His campaign manager, Colin Reed, sent a letter to Mayday PAC's Lawrence Lessig, a professor at Harvard. "Scott Brown is not nor has he ever been a lobbyist. Ever," Reed writes. "We call on you to immediately cease and desist with the mailer in question, and to use one of your various media appearances as a purported authority on ethics to retract your falsehood."

We don't say this is a foolish fight because Reed is wrong; though the matter is not as cut-and-dry as he suggests (more on this — the actual point of this post! — below). It is a foolish fight because Brown is giving free media attention to an organization that barely registers in the public's consciousness. There's not really any chance Rubens will win this week's Republican primary. (In June, Brown outpolled Rubens 10 to 1.) Meaning that all Brown is doing is getting people to spend the last 48 hours before that election talking about whether he is or is not a lobbyist.

Go to Google right now and search for the Streisand Effect. We'll wait.

Anyway, since Brown insists that we debate the question, let's. Has Brown ever been a lobbyist?

In Reed's letter, it's likely that his definition of "lobbyist" overlaps entirely with "lobbyist registered with the federal government." And Brown has never been a lobbyist in the eyes of the federal government, as Daniel Auble, senior researcher for the Center for Responsive Politics pointed out to The Post. "The three criteria laid out by the Lobby Disclosure Act," Auble said, "are that you are getting paid, contact government officials more than once for the client and spend at least 20 percent of your time working on lobbying related tasks for the client." That is what constitutes a registered lobbyist: Someone who meets those standards and whose activity is reported to the government.

In a blog post replying publicly to Reed, Lessig points to coverage of Brown's hire by lobbying firm Nixon Peabody. That announcement reads, in part: "Given his background in public service at both the national and state levels, Brown will focus his practice on business and governmental affairs as they relate to the financial services industry as well as on commercial real estate matters."

"So yes, according to the Senate, Scott Brown isn’t a 'lobbyist,' " Lessig writes. "But I submit to anyone else in the world, a former Senator joining a 'law and lobbying firm' to help with Wall St's 'business and governmental affairs' is to make him a lobbyist."

"To anyone else in the world" is a broad statement. We asked Ben Zimmer, executive producer of and language columnist for the Wall Street Journal, for his assessment of how the word is understood. "It's an interesting case where Congress trying to legislate language and the meaning of words," Zimmer said, adding that "the meaning of words are very slippery things." From the beginning of its usage, there has "always been a general understanding that the role of a lobbyist is to influence legislators." Its application to Brown is "kind of a gray area, obviously," with Zimmer arguing that simply working for the firm not necessarily implying that Brown is doing lobbying.

(Incidentally, the term itself does not originate from men waiting in the lobby of a hotel for President Grant, as legend has it. "There's plenty of evidence that the term predates the Civil War," Zimmer notes, pointing to research conducted by OED contributor Barry Popik. The first mention of "lobby" in the sense we mean dates to 1814 — in Albany, N.Y., not Washington.)

What precisely Brown did at Nixon Peabody isn't clear. If he never spoke with a legislator once, or if he never directed others on their lobbying, it seems clear that he didn't meet either the government's or the popular understanding of what a lobbyist does. But what if he, say, spent 19 percent of his time working legislators or their staff? (As Auble pointed out, Newt Gingrich walked a similar line in 2012, after it was revealed that his firm did work for the lobbying arm of Freddie Mac.) That's the gray area.

The 20 percent rule "provides a lot of leeway for filers," Auble said. To emphasize the point, he pointed to the reaction from the lobbying community after rules around lobbying were tightened. "[I]t seems clear that lobbyists are not fleeing K Street in droves," Auble wrote this year to explain the drop in the number of reported lobbyists, "but rather they are doing similar work for the same companies. Instead of doing it in the public eye, though, they have moved out of sight."

Staying under the minimum percentage is one way, but there are others. The amount of lobbying not captured by official registration was about equal to that which was in 2012, according to analysis from the Sunlight Foundation published last year. "If lobbyists want, they can fully comply with the law and do virtually the same influence-for-pay as strategic policy consultants or historical advisers," the organization's Tim LaPira wrote — "and choose not to disclose."

It's very possible that Reed's letter stipulating that Brown never did any lobbying at all reflects an accurate statement — that Brown never once did anything that, as Zimmer articulates it, would be generally considered lobbying. That's the problem with gray areas: they look either black or white, depending on the light you shine. And unless Brown releases his full work record from Nixon Peabody, we can't know.

We do know why Brown doesn't want to be considered a lobbyist — so much so that he was willing to pick this particularly small-potatoes fight. Last December, Gallup found that Americans listed lobbyists at the very bottom of a list of occupations when measured on trustworthiness. That's two slots lower than car salesmen, the longstanding stereotype of the untrustworthy professional. And it's only one slot below the second-least trustworthy occupation: Congressman.

On the other part of the pejorative description Mayday PAC used in its mailer — that Brown had at one point been a member of Congress — Reed's letter is silent. You pick your battles.