Which are the similarity criteria for trademark search?

The trademark availability search should begin by determining whether the desired mark consists of, or is imitative of, a "famous" trademark, as famous trademark are protected in all the classes even without being registered. Notority of a trademark is examined individually in each country, as the same trademark may be notorious in one country and may not be in another.

Once relation to a famous trademark is ruled out, the primary test of a mark's availability is whether it is identical or confusingly similar in appearance, sound, or meaning to another existing mark for a similar or related product or service.

Legally, the trademark selected cannot be so similar to the already-existing trademark of a related product that it would cause confusion in the minds of the products' purchasers as to the source of the product.

To determine whether confusingly similar marks exist, the searcher must check for exact matches and for variant spellings and phonetic equivalents (e.g. QUICK, QUIK, KWIC, KWIK, KWYK, QUIQUE, etc.).

It is also necessary to check for homonyms, synonyms, and marks with the same prefix, suffix, or mid-word character string, as well as for word mark/design equivalents (e.g. the word mark Pegasus was held to infringe Mobil Oil Company's design mark of the mythical flying horse).

There are many words, prefixes, or suffixes that are used so frequently that they appear in hundreds of marks. (e.g. the letter string "pro"). As a result, it is often necessary to narrow the search to include only marks for related goods or services. This is done by narrowing the results of the initial search by class of goods or services and/or by description of goods or services.

Searching by class requires caution due to inconsistencies in the classification system (e.g. blankets are in International Class 24 and pillows are in International Class 20).

When narrowing the search by class, it's best to include even slightly-related classes to avoid missing relevant marks.

Limiting the search by the descriptions of goods/services is more difficult because the descriptions are those provided by the applicant in the trademark application, and they vary considerably (e.g. one applicant may describe the product as "shoes", another as "footwear"). The searcher must use synonyms and truncated terms to avoid missing marks in a goods/services search.

It should be noted that it takes several weeks for new application information to appear in the registration databases. This means that conflicting marks may not have been added to a database at the time of the search.

To further complicate trademark availability searching, foreign applicants may obtain priority based on the foreign filing date, which can be as much as six months earlier than the registration filing date.

When conducting comprehensive trademark searches, the searcher must search as comprehensively as possible but with the knowledge that there is some risk that there is a conflicting mark somewhere.