a. Carbon Claims: While the US Guide focuses on carbon offsets, other guidelines cover not only that but also "carbon neutral" and similar claims – namely, New Zealand, Australia, Norway, the UK and ISO 14021.

Guidelines in the latter jurisdictions specify what you need to put in your ads by way of qualification – for example, identifying: i) which elements of the life cycle you have "offset"; ii) which "Scopes" ofemissions have been offset (Scopes 1, 2 and/or 3, under the Greenhouse Gas Protocol); iii) what offset scheme you've used; and/or iv) sources of further information about the offset scheme.

b. Public Access to Your Substantiation: The US Guide doesn't recommend, as do ISO 14021 and jurisdictions like Canada and the UK , that companies either release to the public information that verifies a claim or at least provide access to the information on request.

Indeed, ISO 14021 and the UK add the strict kicker that if your claim relies on confidential information for its verification, you shouldn't make the claim. Canada's Guide doesn't go quite that far. It says that if your claim is based on confidential information, you should be prepared to make the substantiation available to a regulator, if asked.

c. Encouraging Bad Environmental Practices: The US Guide doesn't prohibit ads from showing scenes that would encourage pollution or harm to the environment, as some European guidelines and Brazil's guidelines do.

d. Making Consumers Feel Guilty: The US Guide doesn't prohibit, "techniques which manipulate consumers' emotions or conscience," as Norway's guidelines do. Examples of unfair claims in Norway are, "Think of the polar bears: buy energy-efficient insulation." and "Drink coffee with a better conscience."

e. Guidelines for Specific Products: The US Guide doesn't include special guidelines directed to certain product categories, as some other countries have done for vehicles, electricity, energy for house heating, decorative coatings, growing media, greeting cards and cleaning products, for example.

f. Sustainability Claims: The FTC declined to delve into claims of "sustainability." Not so in some other guides. ISO 14021 was clear in its original form that no claim of achieving sustainability should be made. The amendments to ISO 14021 say that no "unqualified" claim of sustain-ability should be made (though without offering any details on the kinds of qualifications that would be appropriate).

Granted, "sustainability" is a bit of a thicket. A good illustration comes from a 2008 case in which Cotton USA was told by the UK selfregulatory Advertising Standards Authority ("ASA") not to call its cotton "sustainable". The advertiser argued that its cotton was natural, biodegradable and renewable and met the criteria of sustainability put forward by a number of major organizations (including the UN) – namely, economical viability, environmental protection and social responsibility.

The challenger was not having any of it and submitted that cotton was a pesticide and insecticide-intensive crop that could seriously deplete groundwater; and, furthermore, that cotton growers in West Africa were having a terrible time because of subsidies granted in the US cotton industry.

The advertiser came back saying that current pesticides were more targeted, less toxic and less persistent in the environment, that the vast majority of cotton was genetically modified, which reduced its need for intensive agriculture, that cotton was not water-intensive, and, furthermore, that there were a number of reasons the cotton growers in West Africa were having a terrible time apart from US subsidies. Of course, there was a division of scientific opinion on a lot of these issues and ASA wasn't sure how clear it was that genetic modification of the cotton, which had allowed some of these benefits, wasn't harmful – etc., etc. One can see why the FTC would say – OK, this is a quagmire; we're not going there (at least yet).

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.