You've cleared all four gates: § 101, § 102, § 103, § 112. Your invention is patentable. Your specification teaches it. Your claims define it.
But there's one more trap waiting: double patenting.
Double patenting prevents you from:
This doctrine exists because the patent bargain gives you 20 years from filing. You can't game the system by filing multiple applications with slight variations to extend your monopoly.
There are two distinct types of double patenting, each with different rules and solutions:
1. Statutory (Same Invention) Double Patenting
2. Obviousness-Type Double Patenting (ODP)
The rule: You cannot get two patents for the same invention.
Statutory basis: 35 U.S.C. § 101 states you may obtain "a patent" (singular) for an invention. This has been interpreted to mean one patent per invention.
Test: Do the claims in two patents/applications define the identical invention?
Patent #1, Claim 1: A widget comprising: (a) a base, (b) a rotating arm, and (c) a spring.
Application #2, Claim 1: A widget comprising: (a) a base, (b) a rotating arm, and (c) a spring.
Analysis: The claims are identical. Same elements, same scope. This is statutory double patenting.
Result: Examiner will reject Claim 1 of Application #2 for statutory double patenting over Patent #1. Cannot be overcome with terminal disclaimer. Must cancel claims in Application #2 or amend to make them patentably distinct.
Patent #1, Claim 1: A widget comprising: (a) a base, (b) a rotating arm, and (c) a spring.
Application #2, Claim 1: A widget comprising: (a) a base, (b) a rotating arm, (c) a spring, and (d) a locking mechanism.
Analysis: Application #2 claim is narrower (adds locking mechanism). Not identical scope. NOT statutory double patenting.
But: Could still be obviousness-type double patenting (if adding locking mechanism is obvious variant).
You can't overcome it with terminal disclaimer. Your only options:
The doctrine: You cannot get two patents where one claim is an obvious variation of the other, if this would extend the patent term.
Key case: In re Berg, 140 F.3d 1428 (Fed. Cir. 1998); Gilead Scis., Inc. v. Natco Pharma Ltd., 753 F.3d 1208 (Fed. Cir. 2014).
Purpose: Prevent inventors from extending monopoly beyond statutory 20-year term by filing continuation applications with obvious variants.
Two-way test: ODP exists if claims in the two patents/applications are not patentably distinct—meaning one would have been obvious over the other.
Analysis similar to § 103: Would the claims of Patent/Application #2 have been obvious in view of Patent/Application #1?
Patent #1, Claim 1: A pharmaceutical composition comprising Compound X.
Application #2, Claim 1: A pharmaceutical composition comprising Compound X and a pharmaceutically acceptable carrier.
Analysis:
Result: Obviousness-type double patenting rejection. CAN be overcome with terminal disclaimer.
ODP typically arises when:
Important: Under pre-AIA law, ODP required common ownership or assignment at time of invention. Post-AIA, common ownership at time of application filing.
ODP requires checking obviousness in both directions:
If either direction shows obviousness → ODP exists.
Patent #1, Claim 1: A widget comprising a base and an arm.
Patent #2, Claim 1: A widget comprising a base, an arm, and a spring.
Direction 1: Is Patent #2 obvious over Patent #1?
→ Yes. Adding spring to base+arm widget is obvious (routine addition of known element).
Direction 2: Is Patent #1 obvious over Patent #2?
→ Yes. Removing spring from base+arm+spring widget is obvious (simple omission of element).
Result: ODP exists in both directions. Terminal disclaimer required.
📖 Margin Story: The Patent Family Game
"You file a continuation," Severen explained, "same disclosure, narrower claims. A year later, your first patent issues. Now your continuation faces obviousness-type double patenting."
Zara frowned. "But my continuation is narrower. How can narrow claims create a double patenting problem?"
"Because if the continuation issues, it expires later than your first patent. You'd have a monopoly on the narrow claims even after the broad patent expires—extending your term." His sapphire eyes gleamed. "The system won't allow that. File terminal disclaimer. Tie the patent terms together. Both expire on the same date."
"So terminal disclaimer is the price of filing continuation applications."
"Exactly. One invention, one patent term. Even if you split it across multiple patents."
The tool: A terminal disclaimer under 37 C.F.R. § 1.321 is a document filed to overcome an obviousness-type double patenting rejection.
Example timeline:
Patent #1: Filed January 1, 2020 → Expires January 1, 2040 (20 years)
Application #2: Continuation filed June 1, 2021 → Would normally expire June 1, 2041 (20 years from filing)
Problem: Application #2 claims are obvious variant of Patent #1. ODP rejection.
Solution: File terminal disclaimer in Application #2.
Result:
To file a terminal disclaimer, you must:
Form: USPTO provides standard terminal disclaimer forms (PTO/SB/25 or PTO/SB/26).
Positive:
Negative:
Important issue: If your patent gets Patent Term Adjustment (PTA) under 35 U.S.C. § 154(b) for USPTO delays, does terminal disclaimer disclaim the PTA days too?
Answer (recent developments): In In re Cellect, the USPTO ruled that terminal disclaimers disclaim PTA. This was controversial and led to changes in how terminal disclaimers are interpreted.
For exam purposes: Terminal disclaimer ties patent terms together. If Reference Patent has PTA, and Disclaimed Patent has PTA, the earlier expiration date controls.
📖 Margin Story: The Terminal Disclaimer Trade
"Terminal disclaimer," Severen said, "is a trade. You give up term. You get allowance."
Zara held the form. "My continuation would expire June 2041. But my first patent expires January 2040. If I file this, I lose 18 months."
"Yes. But without it, your continuation gets rejected for ODP. No patent at all." His sapphire eyes gleamed. "Eighteen months of term vs. nothing. Easy math."
"And both patents must be assigned together. I can't sell one without the other."
"That's the common ownership requirement. The patents are bound together for life." He paused. "This is the price of continuation practice. Multiple patents, but unified term and ownership."
ODP is most common in these scenarios:
What it is: Application with same disclosure as parent, filed before parent issues or abandons. Claims priority under 35 U.S.C. § 120.
Why ODP arises: Continuation typically has narrower claims than parent. When parent issues, continuation faces ODP.
Parent Application: Claims 1-20 (broad to narrow)
Parent Patent issues with Claims 1-10 (examiner allowed these)
Continuation filed with Claims 11-20 (narrower claims from parent that weren't pursued)
Problem: Continuation claims are obvious variants of parent patent claims (just add limitations).
Solution: File terminal disclaimer in continuation over parent patent.
What it is: Application carved out from parent after restriction requirement. USPTO forced election between independent/distinct inventions.
Why ODP arises: If the inventions aren't truly independent and distinct, claims might be obvious variants of each other.
Safe harbor: If restriction requirement was proper (inventions are independent and distinct), ODP shouldn't apply. But sometimes examiner's restriction was questionable.
What it is: Application that adds new matter to parent disclosure. Claims can be drawn to original matter (entitled to parent's priority date) or new matter (gets CIP filing date).
Why ODP arises: Claims drawn to original matter may be obvious variants of parent patent claims.
Scenario: Company has portfolio of related patents filed over several years. Later patents may have claims that are obvious variants of earlier patents.
ODP check: When prosecuting later applications, must check against all earlier commonly-owned patents in related technology.
Understanding the examiner's process helps you respond effectively.
Step 1: Identify reference patent/application
Step 2: Compare claims
Step 3: Determine if differences are patentably distinct
Step 4: Check if terminal disclaimer on file
Typical ODP rejection language:
"Claims 1-10 are rejected on the ground of nonstatutory obviousness-type double patenting as being unpatentable over claims 1-5 of U.S. Patent No. 10,000,000 (the '000 patent) to Smith et al.
Although the claims at issue are not identical, they are not patentably distinct from each other. Claim 1 of the instant application and claim 1 of the '000 patent both require a widget with a base and arm. The instant claim further recites 'a spring connecting the base to the arm.' However, adding a spring to connect base and arm is an obvious variation that does not render the claims patentably distinct.
This is a provisional obviousness-type double patenting rejection because the patentably indistinct claims have not in fact issued in separate patents yet.
This rejection may be overcome by filing a terminal disclaimer in accordance with 37 C.F.R. § 1.321(c) disclaiming the terminal part of the term of the instant patent that would extend beyond the expiration date of the '000 patent."
When to use: For obviousness-type double patenting where claims are not patentably distinct.
How to do it:
Result: ODP rejection overcome. Application proceeds.
When to use: When you believe the differences between claims are NOT obvious.
Arguments to make:
"Applicant respectfully traverses the obviousness-type double patenting rejection.
The claims are patentably distinct from those in the '000 patent. While the '000 patent claims a widget with base and arm, the instant claims require 'a spring made of shape-memory alloy connecting the base to the arm.'
The shape-memory alloy spring produces unexpected results: Unlike conventional springs (steel, rubber), shape-memory alloy provides automatic adjustment to temperature changes, enabling self-correction without external control mechanism (see Spec. ¶¶ 45-50, Fig. 5 showing 50% improvement in stability).
Different utility: The '000 patent claims a widget for manual adjustment. The instant claims enable autonomous adjustment via material properties—fundamentally different function.
The claims are not obvious variants, but patentably distinct inventions. Terminal disclaimer is not necessary."
When to use: When you don't want to file terminal disclaimer (preserve full term) and have support in specification for distinguishing features.
When required: For statutory (same invention) double patenting, terminal disclaimer doesn't work. Must cancel claims.
Strategic choice: Decide which patent/application to keep, which to cancel.
Recognize these patterns instantly:
Pattern: Earlier patent has broad genus claim. Later application has narrow species claim within that genus.
Example:
Analysis: Species claim is obvious variant of genus claim (narrowing to specific species).
Solution: Terminal disclaimer.
Pattern: One patent claims product. Another claims obvious method of making that product.
Example:
Analysis: If method is obvious way to make the product (just routine assembly steps), ODP may apply.
Counter-argument: If method has unexpected advantages (special process conditions, novel technique), may be patentably distinct.
Pattern: One patent claims product. Another claims obvious use of that product.
Example:
Analysis: If using Drug X to treat Disease Y is the obvious and intended use, ODP may apply.
Counter-argument: If the use is unexpected, novel indication, or requires specific dosing regimen not disclosed in first patent, may be patentably distinct.
Pattern: Earlier patent has Markush group (alternative elements). Later application selects different member from same group.
Example:
Analysis: Selecting different member from disclosed alternatives is obvious variant.
Solution: Terminal disclaimer or show unexpected advantage of aluminum over steel.
📖 Margin Story: The Strategic Portfolio
"Smart applicants," Severen said, "build patent families strategically. Parent with broad claims. Continuation with narrow dependent-style claims. CIP adding new embodiments."
Zara traced the family tree. "And terminal disclaimers tie them all together. Same expiration date."
"Yes. But you get defensive depth. Competitor must design around MULTIPLE patents, not just one. Invalidate one patent? Others remain." His sapphire eyes gleamed. "That's the trade. Unified term, but multiplied protection."
"And all expire together. No extension beyond 20 years."
"Correct. One invention, one patent term. But that one invention can be protected by many claims across many patents—as long as you tie the terms together with terminal disclaimers."
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END OF CHAPTER 7 - DOUBLE PATENTING