Patent Strategy

Design-Around Strategy

Claim element analysis, prosecution history estoppel, doctrine of equivalents risk, continuation threats, and design-around vs. license decisions.

What is a design-around and what legal analysis supports it?

A design-around modifies a product or process to avoid infringing a patent's claims.

Definition. Engineering or designing a product or process that achieves the same functional goal as the patented invention without satisfying every element of any claim of the patent

Legal Basis for Design-arounds

The all-elements rule: a patent is infringed only if the accused product or process satisfies EVERY element of at least one claim of the patent
If any element is missing, there is no literal infringement
Therefore: remove or change a single element of the claim → no literal infringement
BUT — the doctrine of equivalents must also be analyzed

Doctrine of Equivalents Risk. Even without literal infringement, a design-around can still infringe if the changed element performs substantially the same function, in substantially the same way, to achieve substantially the same result (function-way-result test; Graver Tank v. Linde Air Products, S.Ct. 1950)

Prosecution History Estoppel Limits DOE

If the patentee narrowed a claim element during prosecution to overcome a rejection (amended or argued to distinguish prior art), the doctrine of equivalents cannot recapture the surrendered territory
Festo Corp. v. Shoketsu Kinzoku Kogyo (S.Ct. 2002): narrowing amendments for reasons substantially related to patentability create a presumptive bar to DOE for the narrowed element

Design-around Framework

Step 1. Obtain the patent and read all claims carefully

Step 2. Map your product or process to each claim element

Step 3. Identify which elements you can change or eliminate

Step 4. Assess DOE risk for each changed element

Step 5. Check prosecution history to see if DOE is barred by estoppel

Step 6. Implement the design-around

Step 7. Document the analysis (supports good-faith belief / willfulness defense).

How does prosecution history estoppel limit design-around options?

Prosecution history estoppel is the design-arounders' most valuable tool.

What Prosecution History Estoppel Does for Design-arounds

It limits the patent owner's ability to use the doctrine of equivalents to capture your design-around
When a claim element was narrowed during prosecution, the patent owner cannot recapture equivalents of the surrendered scope

How to Use it

Search the patent's prosecution history (file wrapper) on the USPTO Patent Center
Look for: amendments that narrowed the claim element you changed
Arguments by the patentee distinguishing prior art on the basis of the specific element
Cancellation of broader claims and substitution with narrower claims

If the Element was Narrowed

Identify what broader scope was surrendered
Design your product to fall in the surrendered scope
The patent owner cannot use DOE to cover your design-around because they surrendered that equivalents range during prosecution

Festo Presumption

When a patentee narrows a claim for a reason related to patentability, there is a presumptive bar to DOE for that element
The patentee can rebut the Festo presumption only by showing: (a) the equivalent was unforeseeable at the time of the amendment
(b) the rationale for the amendment bears no more than a tangential relation to the equivalent
(c) there is some other reason suggesting the patentee could not reasonably be expected to have described the equivalent

Specific Exclusion Principle. If a patent's prosecution history or claims specifically exclude a particular embodiment (explicitly or by necessary implication), that embodiment is not infringed even if it might otherwise be an equivalent

Claim Differentiation. If the patent has dependent claims that add an element absent from the independent claim, the independent claim presumably does not require that element — the design-around can include that element without being limited to the dependent claim's version.

What is the doctrine of equivalents and how does it threaten design-arounds?

The doctrine of equivalents is the patentee's primary tool to capture design-arounds.

DOE Basics

Even when a product does not literally infringe (it lacks one claim element), the patent may still be infringed if the product performs substantially the same function in substantially the same way to achieve substantially the same result as the claimed element
GRAVER TANK v. LINDE AIR PRODUCTS (S.Ct. 1950): established the function-way-result test
The DOE applies element-by-element (not claim-by-claim)
Must show each changed element is equivalent to the corresponding claim element
WARNER-JENKINSON CO. v. HILTON DAVIS CHEMICAL CO. (S.Ct. 1997): reaffirmed DOE
The function-way-result test applies element-by-element
Prosecution history estoppel must be applied on an element-by-element basis
FESTO CORP. v. SHOKETSU KINZOKU (S.Ct. 2002): narrowing amendment for reasons substantially related to patentability = presumptive bar to DOE for that element
Largely gutted DOE for claims that were amended during prosecution

Design-around Strategies to Avoid DOE

Change the Function. Design the altered element to perform a substantially DIFFERENT function — not just a different way to do the same thing

Change the Way. Even if the function and result are the same, perform the function in a substantially different way

Leverage Prosecution Estoppel. Design-around to fall in the surrendered scope — DOE is barred

Use Prior Art as Shield

The Wilson Sporting Goods rule: DOE cannot be used to cover subject matter in the prior art
If your design-around was in the prior art at the time the patent issued, DOE cannot reach it

Specific Exclusion. If the prosecution history explicitly excludes your design-around, DOE is blocked.

What is the continuation risk in design-around strategy?

The patentee can sometimes use continuation applications to capture a design-around.

Continuation Risk. When a design-around becomes public (the product launches), the patentee may file a continuation application with new claims specifically drafted to cover the design-around

Legal Basis. If the patentee has a pending patent application (or a parent application is still open for continuation), the patentee can draft new claims supported by the original disclosure that read on the design-around

How This is Possible

A continuation shares the priority date of the original application
If the design-around uses technology that was described (if not claimed) in the original application, the patentee can now claim it

Limitations

The original disclosure must support the new claims (§ 112 written description)
New matter cannot be added
The claims cannot be broader than the original disclosure

Submarine Patents (Historical)

Pre-AIA, continuation applications could remain pending for decades with undisclosed claims
The patent would 'surface' when a competitor's product matched the eventually-issued claims

AIA 2011

Limited submarine patent risk
Applications publish at 18 months
Term measured from filing date (not issue date)
20-year patent term from earliest effective filing date

Post-aia Continuation Risk

Continuation risk still exists while any related application is pending
At product launch, check: are there any pending continuation, CIP, or divisional applications from the same family?

Design-around Timing

Implement design-arounds before the continuation patent issues, not after
Once the continuation patent issues with claims covering the design-around, you face a new infringement suit

Monitoring Pending Applications. Subscribe to family monitoring (Google Patents Family; Derwent Innovation) to receive alerts when continuation applications file or publish.

How does design-around compare to licensing as a strategic choice?

The design-around vs. license decision is a core IP strategy choice.

Cost-benefit Framework

Cost of Licensing

Royalty rate × sales volume over the license term
Upfront license fee
Time to negotiate
Ongoing compliance burden
Reputational impact (paying a competitor for technology)

Cost of Design-around

Engineering time and cost
Time-to-market delay
Risk of unsuccessful design-around (DOE liability remains)
Risk of continuation patent
Ongoing monitoring

When Design-around is Preferred

The royalty demand is unreasonable or the patent is of questionable validity
The product can be redesigned without significant performance degradation
The patent is held by a competitor who would not grant a license or would impose restrictive terms
The design-around creates an opportunity to develop a superior product (leapfrog innovation)

When Licensing is Preferred

The patent is clearly valid and clearly infringed
The royalty rate is commercially reasonable
Time-to-market is critical and design-around would cause significant delay
The patent holder has demonstrated willingness to license at acceptable rates
The patent is fundamental to the technology and multiple other licensees have already accepted it

Hybrid Approach

Implement the design-around AND negotiate a license
The design-around demonstrates alternatives and weakens the licensor's leverage
Simultaneously negotiating limits the risk if the design-around is ultimately found to infringe

Competitive Intelligence Value of Design-around

The design-around process reveals: which claim elements are critical to the invention
Where the prior art limits the patent scope
Which design choices are not covered by the patent
This intelligence improves both product design and potential invalidity challenges

IPR as a Complement to Design-around

If a strong design-around exists, combine it with an IPR petition to invalidate the patent
A successful IPR eliminates the risk of the continuation capturing the design-around.