Since ancient times consumers have relied on traditional trademarks, typically words, designs, numerals and/or devices, as symbols of uniform quality. Recent developments are enabling traders to rely on less traditional forms of trademarks that appeal to the senses in a different way, namely through color, scent and sound, the adoption of which warrants special consideration. For example, now that the United States Supreme Court has confirmed that trademark protection may exist for a single color, trademark owners in the United States may be even more tempted to adopt single color marks. However, what seems appropriate in one country does not always translate easily into foreign marketplaces.
Whether and how color, sound and scent marks are protected in certain leading jurisdictions, illustrates the challenges in protecting such marks globally.
Colors and color combinations play an important role in distinguishing products in the marketplace, and are particularly useful where traditional marks are not easily understood by consumers (e.g. areas of low literacy). Unfortunately, there is no global uniformity in statutory definitions or relevant case law concerning whether a single color, or a combination of colors, can function as a trademark.
The current United States trademark law does not prohibit the registration or protection of colors per se. Historically, however, United States courts were reluctant to recognize trademarks comprised solely of colors or color combinations. In one case a court denied relief to the plaintiffs against confusing usage of red and white labels on food product containers, quoting from a previous case:
Sometimes a color, taken in connection with other characteristics, may serve to distinguish one's goods, and thus be protected by the courts ... ; but, as a rule, a color cannot be monopolized to distinguish a product ... . The primary colors, even adding black and white, are but few. If two of these colors can be appropriated for one brand of tipped matches, it will not take long to appropriate the rest. 
These courts considered that a color per se could not function as a trademark, even though color may be an important feature of a distinctive design or word mark, and they feared that the colors available to traders within a particular field would be exhausted if they protected colors per se as trademarks, the so-called "color depletion" rule.
With time trademark registrability standards have been relaxed and single color marks have now been recognized as registrable and enforceable in the United States. While not discarding the color depletion theory, the Court of Appeals for the Federal Circuit rejected an absolute prohibition on the registrability of a trademark comprised solely of the color pink as applied to residential fibrous glass insulation, stating that each case must be judged by the individual facts and circumstances, taking into consideration "the liberating purposes of the [Lanham] Act." The court found that the color had no utilitarian purpose with respect to the goods and that granting protection would not deny competitors a reasonable right or competitive need. Furthermore, the evidence established that the color "pink" functioned as a trademark.
However, until recently, United States courts were still divided over the issue of single color marks. Finally, on March 28, 1995 the United States Supreme Court resolved unanimously that, "sometimes, a color will meet ordinary legal trademark requirements. And, when it does so, no special rule prevents color alone from serving as a trademark." However, the Court held implicitly that single colors may not be inherently distinctive, but like descriptive marks or words, may only be protected when they have acquired a secondary meaning through use. The Court also found that the green-gold color at issue served no function other than as an identifier and the Court dismissed the "color depletion" problem raised by the plaintiffs.
The United Kingdom has also recognized and registered colors as trademarks, e.g., the color silver in connection with anthracite briquettes, the color red applied to the pin of a shackle, three red bands on the handle of tennis, badminton, and squash rackets, and the color green applied to the exterior surface of a building. However, registrants may be required to prove that the colors had acquired distinctiveness through prior use or, if the color to be registered is the color of the goods themselves, proof or assurance that the color serves no function other than as a trademark may be requested.
Unregistered color marks have also been protected in the United Kingdom under the theory of passing off, a type of unfair competition, albeit inconsistently. Green and black pharmaceutical tablets were considered sufficiently distinctive of a manufacturer so as to prevent use of the same color scheme by another trader. However, a pharmaceutical manufacturer was unable to prevent use of its yellow and white color coding system for tablets of different dosages. Although seemingly inconsistent, success in passing off actions depends much on the specific facts and the extent to which the colors at issue have become distinctive of a particular party.
The United Kingdom Trade Marks Act was recently revised to conform to the European Community Trademark Harmonization Directive ("Directive"), which has also driven changes in the laws of other European Union and European Free Trade Association member states, and numerous other countries. Although the Directive sought to harmonize the definition of a trademark, it remained silent on the issue of color marks, instead, stating in Article 2 that:
a trademark may consist of any sign capable of being represented graphically ... provided that such signs are capable of distinguishing the goods or services of one undertaking from those of other undertakings.
Thus, each member state may determine whether a color or combination of colors complies with this definition. For example, the French Trademark Law of 1991, based on the Directive, defines a trademark as including "arrangements, combinations or shades of colors" and permits registration of single colors and combinations of colors. However, since the Trademark Office does not apply strict standards in its registrability examination, the discretion to enforce registered rights remains with the courts.
Although the new German Marks Act, effective January 1, 1995, specifically includes colors and combinations of colors as registrable marks, recently issued internal guidelines of the Patent Office appear to exclude registration for such marks, unless combined with other distinctive features, and it is likely that the courts will need to rule on this issue. Under the former Act, the courts protected colors provided they had acquired secondary meaning in the relevant trade circles, e.g, the color combination red and yellow  and the color combination blue and white for gas stations; and the red point of an umbrella in combination with the graphical point element. However, single colors were not protected absent sufficient evidence of secondary meaning.
The Regulation on the European Community Trademark has adopted the Directive's wording, leaving unresolved how the Community Trademark Office will treat such applications and how national courts will interpret the validity of Community Trademark registrations in trademark infringement cases.
The position is even less consistent in other countries where colors may or may not be registered as marks or protected like trademarks under other legal theories. Negotiations in the late 1980's for a multilateral treaty to harmonize substantive and procedural provisions of national trademark laws illustrated the absence of an international standard regarding color marks. The proposed definition of a registrable sign that included "colors" was deleted, since numerous national delegations protested that "only color combinations could be protected in their countries."
The Uruguay Round of the General Agreement on Tariffs and Trade concluded, inter alia, with an agreement on the Trade Related Aspects of Intellectual Property Rights (GATT-TRIPS), which states:
combinations of colors...shall be eligible for registration as trademarks [although] members may make registrability depend on distinctiveness acquired through use [and] members may require, as a condition of registration, that signs be visually perceptible."
Therefore, the over one-hundred anticipated GATT-TRIPS adherents must accept color combination marks for registration, although protection may be conditioned on the combination having acquired distinctiveness through use. The agreement is silent on the issue of single color marks.
Older Australian cases adopted a more restrictive approach to protecting colors than the United Kingdom. However, the new Trade Marks Act that entered into force on January 1, 1996, now includes "any colour" as a registrable sign. Also, more recent cases in Australia and New Zealand have protected colors, absent registration, under the theory of passing-off.
The Mexican Industrial Property Law prohibits registration of "isolated colors, unless ... combined or accompanied by elements such as signs, designs or designations that make them distinctive." The Supreme Court has also affirmed that a combination of colors, and even one single color, would be registrable as a trademark provided the mark consists not only of a color but of a color combined with a distinctive sign. The unfair competition laws do not protect single color marks either.
Since the Brazilian Industrial Property Code specifically prohibits the registration of "colors and the names thereof unless combined in an original manner", single colors are not registrable although combinations of colors combined in some distinctive manner may be registrable. Moreover, the courts have refused to protect a single color as a trademark, for example, the color yellow in respect of hand saws, notwithstanding substantial use.
The South Korean trademark law was amended on January 1, 1996, to include color or combinations of colors as part of a registrable mark, although color alone is still not protected. Even though Korean courts have not addressed protection for color marks, Article 2(1) of the Unfair Competition Prevention Act theoretically prevents the unauthorized use of a color on products for which the color has become well-known in Korea as the mark of a particular party.
Although Chinese law does not permit the registration of single colors, a combination of colors may be registered where the combination has acquired distinctiveness through use. The courts have not addressed color mark protection.
Taiwan does not allow registration of single color marks, although a combination of colors that has acquired distinctiveness through substantial use may be registrable. Apparently the courts have not considered color marks, although the Fair Trade Commission is considering at least one case concerning the unauthorized use of an unregistered combination of two colors under the Fair Trade Law.
Japan does not permit registration of single color or color combination trademarks, without other identifying or distinctive features, and there are no judicial decisions which have addressed such issues.
Even though trademarks consisting of sounds have existed for many years, there is no uniformity regarding protection for such marks in the global marketplace.
The United States has long recognized sound marks, such as the familiar chimes of the National Broadcasting Corporation (NBC). Even Harley Davidson is attempting to register the "roar" of its motorcycle engine. Although certain sound marks may not be considered inherently distinctive, they may be registrable upon proof of secondary meaning.
There is no uniform protection on the international level.
As with color marks, even more delegations in the Trademark Law Treaty negotiations expressed reservations as to whether sounds could constitute a mark under their national laws. The GATT-TRIPS Agreement, the EU Directive and the Community Trademark Regulation are all silent on sound marks. However, GATT member states may exclude protection for sound marks by requiring that registrable signs be visually perceptible.
Even if permitted by statute, registration of sound marks may be frustrated by the practical difficulties of sufficiently describing such marks to satisfy local Trademark Offices.
The new United Kingdom Trade Marks Act neither includes nor excludes protection for sound marks, presumably permitting registration of sound marks that are capable of graphic representation and capable of distinguishing goods or services of one undertaking from another. Sound marks are registrable and enforceable in France since the legal definition of a trademark expressly includes "sound, musical phrases, arrangements, combinations."
Although previously unregistrable, sound marks are protected under the new German Marks Act because they are capable of graphic representation. Apparently the courts have not considered whether unregistered sound marks are protected under a theory of unfair competition.
Contrary to the previous law, the new Australian Trade Marks Act expressly provides that sound may constitute a "sign", and sound marks should now be registrable and enforceable.
The Mexican Industrial Property Law does not allow registration of sound marks since marks must be visually perceptible. Moreover, the courts have not yet considered the theoretical possibility of sound mark protection under the doctrine of unfair competition.
Sound marks cannot be registered in Brazil and the proposed Trademark Act limitation of trademark registration "visually perceptible" signs will apparently exclude sound mark protection. Moreover, the courts have not addressed the protection of unregistered sound marks.
Although South Korea does not provide for the registration of sound marks, it may be possible to protect such marks on the basis of the Unfair Competition Prevention Act, discussed above.
Sound marks are neither registrable nor otherwise enforceable under related laws in many countries, such as China, Taiwan or Japan.
In view of the inconsistency in protection for sound marks, trademark owners with multinational interests must be wary of adopting such marks, since they will be difficult, if not impossible, to register at foreign trademark offices or protect in the courts of many jurisdictions.
Marks consisting of scents are the most problematic. In addition to the practical difficulties of describing such marks sufficiently to determine where conflicts may exist, there is little legislation or jurisprudence on the subject. A scent mark was first recognized in 1990 in the United States, where a scent, described as a high impact, fresh, floral fragrance reminiscent of plumeria blossoms, applied to sewing thread, was deemed a registrable trademark.
The international marketplace does not appear as welcoming. As discussed above, neither the GATT - TRIPS Agreement, the EU Directive nor the Community Trademark Regulation address protection for scent marks. The new United Kingdom Trade Marks Act neither provides for nor prohibits protection for scent marks, thereby presumably allowing registration of scents, although time and practice will tell.
Likewise, registration of fragrance marks in France and Germany is not expressly excluded, although such marks require graphical representation, which may make them difficult to register under current practice. There also appear to be no judicial decisions concerning the protection of such marks under other theories such as unfair competition.
The new Australian Trade Marks Act expressly provides that a scent may constitute a "sign", although there appear to be no cases addressing fragrance mark protection under the former Act.
Most countries of the world will likely choose to refuse protection for scent marks at their Trademark Offices. However, a window of opportunity may exist in the courts. In Mexico, for example, scent marks are unregistrable but it may be possible, although as yet untried, to protect distinctive scent marks under a theory of unfair competition.
Although the South Korean Trademark Act does not provide for the registration of scent marks, the Unfair Competition Prevention Act may protect scent marks, as with color and sound marks.
The door is firmly closed in most other countries, such as Brazil, Japan, China and Taiwan, where scent marks are neither registrable and the courts do not appear to have considered the protection of unregistered scent marks under other legal theories.
The international standards that determine which signs qualify as distinctive and enforceable trademarks have been progressively relaxed. However, even though color, sound and scent marks should be capable of trademark registration and protection, significant obstacles to effective international protection remain. As a result, enterprises adopting color, sound or scent marks in the United States will be frustrated by inconsistencies among the various foreign legal systems. Accordingly, appealing to the senses of consumers may seem a good idea from a marketing perspective, but may not make sense in the realm of trademarks.