The discussion in the First Circuit decision from February 25, Gallo v. Parent,
http://www.ca1.uscourts.gov/ touches upon an interesting First Amendment issue that comes up once in a while in Maine: when an location becomes a public forum for speech.
The holding in Gallo is that the government can restrict campaigning activity on a sidewalk in front of a post office in Pittsfield, Mass. The plaintiff was attempting to gather signatures for nomination papers for public office. There's a plurality Supreme Court opinion that concluded that a sidewalk in front of a post office wasn't a public forum for speech (Kokinda, 497 U.S. at 727, 730). Looking at the historical use of the sidewalk here and finding that it did not have the characteristics of public sidewalks traditionally open to expressive activity, and it was separate from nearby municipal sidewalks, among other things, the First Circuit agreed with the plurality.
So if you want to rely on a federal right to express your views on governmental property not historically used for public speech, you are probably out of luck at least within the First Circuit.
The specific issue where a petition-gatherer must be allowed to gather signatures is one that can come up in Maine and elsewhere, becauses of citizen initiative and referenda laws.
For example, sometimes people argue that they have the right to gather signatures at malls, private property, because, they say, the mall is the modern equivalent to the old town square. It is very clear that they are wrong under federal law - Lloyd Corp. v. Tanner, 407 U.S 551 (1972); Hudgens v. NLRB, 424 U.S. 507 (1976) - but a handful of states, including Massachusetts (Batchelder v. Allied Stores International, Inc., 445 N.E.2d 590 (Mass. 1983)) have found some limited rights under their state constitutions. Massachusetts, focusing on particular right to citizen petition language in its Constitution, found a right to enter for that specific purpose in a large mall, and California recently affirmed a public forum right in malls under the California Constitution (Fashion Valley Mall v. NLRB, 42 Cal.4th 850 (2007)).
What about Maine? Are we going to be confronted with speechifying as we roll our cart down the local Wal-Mart? There's no SJC decision on point, but it's not likely.
Since this is a blog and not a treatise, I will cut to the chase: among other things, viewing private property like a mall as a public forum is a very minority view among the states; to the extent a state does find such a right, it's only for very big malls with areas for the public to congregate, not single stores (even big ones); Maine doesn't have the equivalent petition clause on which the Mass SJC relied; Maine has traditionally interpreted its free speech clause co-extensively with its federal counterpart; and Maine's clause is identical to the clause in 33 other states, the majority of which find no public forum right on such property. I would add that there's been increasing protection of the right not to speak, and so an argument by property owners that allowing someone else to say something on their property that they don't like violates their own speech rights could also have some heft.
Having such a public forum right on private property would also create a lot of messy issues (and so employ more lawyers, hmmm) – when does the property became big enough or public enough to meet the minority criterion for public forum status? what are reasonable time, place, manner restrictions? Is the right limited to certain types of speech, like petition gathers, as in Massachusetts? and so on.
When you open a forum for the public, moreover, that means everybody gets to speak, or at least there's no content-based restriction allowed. So, for example, as we have noted to past Maine Attorneys General, who have agreed with us, if a town decides to allow petition gatherers to come into a building when people are voting, the town must let in people who want to argue against the petition, too. If there's no room for both, the town can't choose one side.
In sum, if it's private property in Maine, owners very likely can choose what speech they wants there – they can let the Salvation Army in and keep the Satanic cults out if they choose. If it's public property, then if it's a public forum opened up for speech (e.g. not a post office sidewalk segregated from the public walk but rather the front of a town hall that the town has decided will be open to petition gatherers), then the government cannot be selective about the speech allowed and can only impose content-neutral time, place, manner restrictions.