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Ninth Circuit

Ninth Circuit Likelihood of Confusion Factors

Ninth Circuit Likelihood of Confusion Factors

Get the expertise you need plus the experience you want.

Each of the thirteen federal courts of appeal have their own test for evaluating whether a likelihood of confusion exists between two trademarks. Although the tests are not identical, most of them are substantially similar and use many of the same factors. And the factors are non-exclusive.

The Ninth Circuit includes the following jurisdictions:

  • District of Alaska
  • District of Arizona
  • Central District of California
  • Eastern District of California
  • Northern District of California
  • Southern District of California
  • District of Hawaii

The Ninth Circuit uses the Eight Sleekcraft Factors when considering likelihood of confusion cases:

  1. The strength of the mark
  2. The proximity of the goods
  3. The similarity of the marks
  4. Evidence of actual confusion
  5. The marketing channels used
  6. The type of goods and the degree of care likely to be exercised by the purchaser
  7. The defendant’s intent in selecting the mark
  8. The likelihood of expansion of the product lines

AMF Inc. v. Sleekcraft Boats, 599 F.2d 341, 348-49 (9th Cir.1979).


In the Ninth Circuit, trademark survey expert Ms. Harper has been retained for 26 cases.

Rhonda Harper Expert WitnessMs. Harper has been retained for cases filed in the:

  • Northern District of California
  • Southern District of California
  • California Central District
  • Superior Court of the State of California for the County of Los Angeles, Central District
  • Central District of California, Central Division
  • Superior Court of California County of San Diego
  • Central District of California Eastern Division Riverside
  • Eastern District of California
  • Nevada Southern Division
  • Western District of Washington at Seattle
  • Superior Court of the State of Arizona in and for the County of Maricopa
  • Northern District of California, Jose Division
  • Northern District of California, San Francisco Division

Beginning her career in consumer package goods, Ms. Harper is a data-driven marketer who has conducted and/or overseen thousands of research studies. Ms. Harper's experience includes leading the research departments for both Sam's Club and VF Corporation VFI - both of which spent millions of dollars every year on custom research. In addition, for eight year Ms. Harper owned and led RTM&J, a boutique management, marketing, and research firm.

Ms. Harper has been retained by more than 100 law firms to formulate expert surveys, conduct rebuttal critiques, or construct rebuttal surveys to show the potential difference in results with properly designed and executed surveys. She has extensive experience and a deep understanding of survey design, sampling, question construction, data analysis, and methodological pitfalls that introduce bias or systematic error.

Consumer opinions, behavior, and potential confusion are key issues in Lanham Act litigation and TTAB proceedings. Ms. Harper develops surveys and analyze these issues in relation to trademark or trade dress infringement, dilution, secondary meaning, and genericness or descriptiveness. She uses only the most advanced online survey platform methods: representative panels, various question types and formats, real-time results, advanced rotation/randomization, quota building, skip and display logic, audio/video/image capabilities, and advanced screening and analytics capabilities.

Ms. Harper has completed scores of rebuttal reports and surveys.

Thorough review and response to an opposing expert’s survey work is a critical component of a successful rebuttal strategy. Ms. Harper provides guidance on how to approach the opposing counsel’s evidence in order to make a strong, effective rebuttal, including crafting effective critiques or constructing rebuttal surveys.

Ms. Harper evaluates the quality and reliability of opposing counsel's survey evidence. She provides assessments of the degree to which surveys conform to generally-accepted principles of proper survey research. She have extensive experience and a deep understanding of survey design, sampling, question construction, data analysis, and methodological pitfalls that introduce bias or systematic error.

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