U.S. Patent 3,563,235: Scope, Claims, Expiration, and Copper IUD Patent Landscape

U.S. Patent No. 3,563,235 covers contraceptive use of elemental metals in the uterine cavity, including copper and zinc, metal-containing intrauterine devices, pharmaceutically acceptable alloys, galvanically coupled dissimilar metals, and a minimum exposed metal area. The patent issued on February 16, 1971, and its enforceable term expired in 1988 under the pre-URAA 17-year-from-issue patent term. It has no current blocking effect on copper IUD development, manufacture, FDA approval, or launch.

What invention does U.S. Patent 3,563,235 cover?

The patent claims the use of elemental metal placed in the uterus to produce a contraceptive effect. Its claim structure has two principal categories:

Method claims covering placement of metal in the uterine cavity.
Device claims covering an intrauterine contraceptive device containing elemental copper or zinc.

The supplied claims depend on claim 1 or claim 7. The omitted text of claim 1 limits the scope of claims 2 through 6 and is material to a complete infringement analysis. Based on the supplied claims, the patent’s core inventive concept is the local contraceptive activity of elemental metal, particularly copper, retained in the uterine cavity over a prolonged period.

What are the limitations of claims 2 through 8?

Claim	Claim type	Principal limitations	Practical scope
2	Dependent method	Metal attached to an IUD and retained in the uterine cavity for a prolonged period	Covers a metal-bearing IUD used as part of the claimed contraceptive method
3	Dependent method	Metal is in a pharmaceutically acceptable alloy	Extends the metal concept beyond substantially pure elemental metal
4	Dependent method	Two dissimilar pharmaceutically acceptable metals contact each other; at least one is copper or zinc	Covers a galvanic or electrochemical metal combination
5	Dependent method	The dissimilar metals are silver and copper	Narrow species claim within claim 4
6	Dependent method	Exposed metal surface area is at least about 20 mm²	Adds a quantitative surface-area threshold
7	Independent device	IUD adapted for insertion and prolonged retention; contraceptively effective amount of elemental copper or zinc	Principal apparatus claim
8	Dependent device	Claim 7 device with exposed metal area of at least about 20 mm²	Narrows claim 7 by adding surface area

How broad is claim 2?

Claim 2 requires the metal to be attached to an intrauterine device. A product in which copper is merely placed in the uterine cavity without attachment to an IUD would not satisfy the added limitation of claim 2, although it could potentially implicate claim 1 if that claim covers such placement.

The phrase “effective to retain said metal in the uterine cavity over a prolonged period of time” focuses on retention rather than a particular IUD geometry. A T-shaped frame is not expressly required by the supplied claim language. The claim therefore reaches devices with different structural configurations if they attach the claimed metal and retain it in the uterus.

What does claim 3 protect?

Claim 3 covers a pharmaceutically acceptable alloy containing the claimed metal. Its importance is that it is not limited to copper or zinc in substantially pure form.

The claim raises two construction issues:

The alloy must contain the elemental metal required by claim 1.
The alloy must be pharmaceutically acceptable for the claimed uterine application.

A copper alloy could fall within the claim if copper remains the relevant elemental metal and the composition satisfies the patent’s pharmaceutical-acceptability requirement. A device using a copper compound, copper salt, or surface coating that does not meet the claim’s “elemental metal” limitation would require separate analysis.

What does claim 4 protect?

Claim 4 requires:

Two dissimilar metals;
Both metals pharmaceutically acceptable;
Contact between the metals; and
At least one metal selected from copper or zinc.

The contact requirement is significant. Two separate metal components located in the uterus but electrically isolated from each other may not satisfy the literal “in contact with each other” limitation. The claim appears directed to a metal pair capable of producing an electrochemical interaction, although the claim text supplied does not expressly require a measured galvanic current or a particular ion-release rate.

How narrow is claim 5?

Claim 5 is limited to silver and copper as the dissimilar metal pair. Because it depends on claim 4, it also inherits the requirements for pharmaceutical acceptability and physical contact.

A silver-copper IUD or uterine metal assembly could fall within claim 5 if it also satisfies every limitation of claim 1. A copper-only device would not infringe claim 5 because the claim requires both silver and copper.

What is the significance of the 20 mm² limitation in claims 6 and 8?

Claims 6 and 8 require an exposed metal surface area of “at least about 20 square millimeters.” This is a quantitative limitation, but “about” introduces a boundary issue. The relevant measurement would likely concern the metal surface exposed to the uterine environment, not the total surface area enclosed within a polymeric IUD frame.

Potential dispute points include:

Whether coated or partially embedded metal is exposed;
Whether both sides of a metal wire are counted;
Whether the measurement is made before or after insertion;
Whether the area includes a portion covered by tissue, biofilm, or deposits; and
How much variation is permitted by “about 20” mm².

Claim 8 is materially narrower than claim 7. A copper IUD with less than approximately 20 mm² of exposed copper could potentially remain within claim 7 while falling outside claim 8, assuming all other limitations are met.

What does claim 7 protect?

Claim 7 is the principal device claim in the supplied claim set. It requires an intrauterine contraceptive device that:

Is adaptable to insertion into the uterine cavity;
Is capable of prolonged retention in the cavity; and
Includes a contraceptively effective amount of elemental copper or zinc.

The claim does not expressly require:

A T-shaped structure;
A particular copper mass;
A copper wire rather than copper sleeves or bands;
A hormone;
A specified release rate;
A particular polymer;
A specific insertion tube; or
The 20 mm² surface-area threshold in claim 8.

The phrase “contraceptively effective amount” is a functional limitation. It links the amount of copper or zinc to contraceptive performance, rather than setting a fixed mass. The claim therefore has broad conceptual coverage but may require technical evidence concerning whether a particular metal amount and device configuration produce the required contraceptive effect.

When did U.S. Patent 3,563,235 expire?

Event	Date
Patent issued	February 16, 1971
Applicable term regime	17 years from issue
Ordinary expiration	February 16, 1988
Current enforceability	Expired
Current patent blocking risk	None

U.S. Patent 3,563,235 was issued before the Uruguay Round Agreements Act changed the term for most later-filed U.S. patents to 20 years from the earliest effective nonprovisional filing date. Under the applicable pre-URAA regime, the patent term ran 17 years from issuance. The patent therefore expired decades ago. No patent-term extension or patent-term adjustment could restore an expired patent.

An expired patent can remain relevant as prior art, but it cannot support an infringement action for activities occurring after expiration.

What is the FDA and Orange Book status of this patent?

U.S. Patent 3,563,235 is not a current Orange Book patent for an approved drug product. Copper IUDs are medical devices regulated through the FDA device framework, not as conventional drug products listed in the Orange Book.

The FDA approved the ParaGard T 380A copper intrauterine contraceptive in 1984 under device regulation. The product uses copper on a plastic frame and has been commercialized through successive manufacturers, including Teva and CooperSurgical. FDA device approval does not establish ownership of, or continuing rights under, the expired patent.

Does the patent create a Paragraph IV issue?

No. Paragraph IV certifications apply to patents listed in the Orange Book in connection with abbreviated new drug applications. U.S. Patent 3,563,235 is expired and does not create a current Paragraph IV barrier for a generic drug applicant.

A competing copper IUD would generally be evaluated under the applicable medical-device pathway, including 510(k), de novo, or PMA-related requirements depending on the product and FDA classification. The relevant regulatory pathway is separate from the expired patent.

What is the current copper IUD patent landscape?

The original patent is part of the foundational patent history for metal-bearing IUDs. It is no longer the principal commercial barrier. Current risk is more likely to arise from later patents covering specific device designs, manufacturing processes, insertion systems, packaging, sterilization, or clinical-use features.

Technology area	Historical relevance of U.S. 3,563,235	Current commercial relevance
Elemental copper in the uterus	Directly addressed	Broad concept is public domain
Copper attached to an IUD	Directly addressed by claim 2	Later structural patents may still matter
Copper or zinc alloy	Addressed by claim 3	Composition and corrosion patents may be relevant
Silver-copper contact	Addressed by claim 5	Narrow historical subject matter
Minimum exposed area	Addressed by claims 6 and 8	Product-specific surface-area claims may be later-filed
T-shaped copper IUD	Not expressly required by supplied claims	Later design and manufacturing patents may apply
Copper release rate	Not expressly quantified	Potential subject of later formulation or materials patents
Hormonal IUS technology	Outside the supplied claim set	Separate patent estates
Insertion and retrieval systems	Not expressly claimed	Potential current design-around and device-IP issues

How does the patent compare with competing contraceptive products?

Product category	Active component	Main patent risk today	Relation to U.S. 3,563,235
Copper IUD	Elemental copper	Later device, manufacturing, and regulatory rights	Technically closest
Levonorgestrel IUS	Hormone	Drug-device combination patents and regulatory exclusivity	Outside the patent’s metal claims
Oral contraceptives	Synthetic hormones	Drug patents, formulation patents, and regulatory exclusivity	Unrelated
Implantable contraceptives	Progestin	Implant and drug-device patents	Unrelated
Nonhormonal investigational IUDs	Various materials or agents	New composition and device claims	May build on or design around the public-domain concept

Mirena, Kyleena, Skyla, and Liletta rely on levonorgestrel release rather than elemental copper. Their patent estates are directed primarily to hormone formulations, reservoirs, release systems, device geometry, and use methods. They do not depend on U.S. Patent 3,563,235.

Are there biosimilar or generic-entry risks?

There is no biosimilar issue because the claimed technology is not a biologic. There is also no current generic-drug exclusivity created by this patent.

A competing copper IUD could face:

Device classification and FDA submission requirements;
Clinical evidence requirements;
Manufacturing validation;
Sterilization and packaging controls;
Biocompatibility testing;
Mechanical retention and retrieval testing;
Copper composition and corrosion controls; and
Later-filed third-party patents.

Those barriers are regulatory, technical, and commercial rather than rights under Patent 3,563,235.

Which companies challenge or license this patent?

No current Paragraph IV challenger, active licensee, or enforceable settlement can be attributed to U.S. Patent 3,563,235 because the patent expired in 1988. Historical commercialization of copper IUD technology involved organizations associated with development and distribution of copper-bearing IUDs, including the Population Council and commercial manufacturers. The patent record alone does not establish the terms of any historical license, royalty arrangement, or settlement.

There is no present litigation exposure under this patent. Any current dispute involving a copper IUD would necessarily depend on later patents, trade secrets, product liability theories, regulatory issues, or contract rights.

How strong is the patent estate for a new copper IUD?

The estate represented by U.S. Patent 3,563,235 is legally extinguished but historically broad. Its claims reached the central concept of using elemental copper or zinc in a retained intrauterine device. That concept is now available for public use.

A new entrant should assess later patent families in these areas:

Frame geometry and arm configuration;
Copper wire winding and attachment;
Copper sleeves, beads, or collars;
Surface-area optimization;
Controlled copper-ion release;
Anti-inflammatory or anti-infective coatings;
Insertion tubes and deployment systems;
Retrieval strings and visibility markers;
Sterilization and packaging;
Manufacturing tolerances; and
Combination products containing copper and another active agent.

The expired patent is therefore a low-risk freedom-to-operate reference but a high-value prior-art document for novelty and obviousness analysis.

Key Takeaways

U.S. Patent 3,563,235 covers elemental-metal contraception in the uterus, especially copper and zinc IUDs.
Claims 2 through 6 are method claims; claims 7 and 8 are device claims.
Claim 7 is the broadest supplied device claim.
Claim 8 adds an exposed-metal threshold of at least about 20 mm².
Claim 5 is a narrow silver-copper species claim.
The patent issued February 16, 1971, and expired February 16, 1988.
It is not a current Orange Book patent and creates no Paragraph IV barrier.
It creates no current biosimilar or generic-drug exclusivity issue.
Current freedom-to-operate risk must be assessed against later patents covering copper IUD structure, manufacturing, insertion, materials, and regulatory design features.
The patent remains relevant as prior art but cannot support a current infringement claim.

FAQs

Can a company manufacture a copper IUD without licensing U.S. Patent 3,563,235?

Yes. The patent expired in 1988, so no license is required under that patent.

Does a copper IUD need at least 20 mm² of exposed copper?

No. The 20 mm² limitation appears in claims 6 and 8, not necessarily in every claim. It is not a current regulatory requirement created by the expired patent.

Does U.S. Patent 3,563,235 cover hormonal IUDs?

No. The supplied claims are directed to elemental metals, principally copper and zinc. Hormonal IUDs rely on separate active ingredients and patent estates.

Could a copper alloy IUD infringe claim 3?

It could have fallen within claim 3 during the patent term if it met all inherited claim 1 limitations and used a pharmaceutically acceptable alloy. The expired patent now creates no enforceable infringement risk.

Is ParaGard protected by U.S. Patent 3,563,235 today?

No. ParaGard and competing copper IUDs are not currently blocked by this expired patent. Any present protection would have to arise from later patents, regulatory rights, trademarks, contracts, or confidential manufacturing technology.

References

U.S. Patent and Trademark Office. (1971). Intrauterine contraceptive device, U.S. Patent No. 3,563,235.
U.S. Food and Drug Administration. (1984). ParaGard T 380A intrauterine copper contraceptive: Device approval and labeling materials.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations (Orange Book).
U.S. Code, Title 35, § 154. (2024). Contents and term of patent; provisional rights.
U.S. Patent and Trademark Office. (2024). Manual of Patent Examining Procedure, Chapter 2700: Patent term.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Canada	941254	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 3,563,235

Summary for Patent: 3,563,235