1. What is “API Cloning” in Legal Terms?

API cloning typically means:

• Recreating another company’s API endpoints
• Copying request/response structure
• Mimicking parameters and function calls
• Allowing software compatibility with an existing system

Example:

• Company A creates API: /getUser?id=123
• Company B replicates same structure so apps can switch without modification

2. Core Legal Issues in API Copyright Disputes

(A) Copyright Law Protection

Copyright protects:

• Source code (literal code)
• Original expression in software
• Documentation (in some cases)

Copyright does NOT protect:

• Ideas
• Methods of operation
• Functional systems
• Interfaces (depending on context)

(B) “Merger Doctrine”

If there is only one or limited ways to express a function:

Expression merges with idea → NOT copyrightable

This is crucial in API cases.

(C) “Fair Use Doctrine”

Courts evaluate:

• Purpose of use (commercial vs transformative)
• Nature of copyrighted work
• Amount used
• Market impact

(D) Interoperability Principle

Courts often allow copying when needed for:

• Compatibility
• Software integration
• System communication

3. Key U.S. Case Laws on API / Software Cloning Disputes

1. Oracle America, Inc. v. Google LLC (2018–2021, Supreme Court)

Facts:

• Google copied Java API declarations into Android
• 11,000 lines of API structure replicated

Issue:

Is copying API structure copyright infringement?

Holding:

• Supreme Court: Google’s use was fair use

Key Principle:

Even if APIs are copyrighted, copying them for interoperability and transformation can be fair use.

Impact:

• Strong precedent favoring software compatibility
• Reduced copyright protection for API structures

2. Lotus Development Corp. v. Borland International (1996, 1st Circuit, affirmed by Supreme Court)

Facts:

• Borland copied Lotus 1-2-3 menu command structure

Issue:

Is a software “menu command system” copyrightable?

Holding:

• NOT copyrightable → “method of operation”

Key Principle:

Functional command structures are methods of operation, not protected expression.

Impact:

• Foundation case for API functionality being uncopyrightable

3. Apple Computer, Inc. v. Microsoft Corp. (1994, 9th Circuit)

Facts:

• Apple claimed Microsoft copied GUI interface elements

Issue:

Are interface elements protected expression?

Holding:

• Most elements were functional or licensed, not protected

Key Principle:

Functional interface elements and “look and feel” require strong originality proof.

Impact:

• Narrowed scope of interface copyright claims
• Influences API UI/UX disputes

4. Sega Enterprises Ltd. v. Accolade, Inc. (1992, 9th Circuit)

Facts:

• Accolade reverse-engineered Sega code to build compatible games

Issue:

Is reverse engineering copyright infringement?

Holding:

• Allowed under fair use

Key Principle:

Reverse engineering for interoperability is fair use.

Impact:

• Strong support for API cloning for compatibility purposes

5. Sony Computer Entertainment v. Connectix Corp. (2000, 9th Circuit)

Facts:

• Connectix created a PlayStation emulator by reverse engineering BIOS

Issue:

Is copying software structure for emulation allowed?

Holding:

• Yes, fair use applies

Key Principle:

Intermediate copying for functional compatibility is lawful.

Impact:

• Supports API replication when building compatible systems

6. Atari Games Corp. v. Nintendo of America (1992–1994, Federal Circuit)

Facts:

• Atari reverse-engineered Nintendo security system

Issue:

Was copying system code infringement?

Holding:

• Some copying was infringement, but reverse engineering for interoperability was partially allowed

Key Principle:

Illegally obtained code is not protected, but clean reverse engineering may be allowed.

Impact:

• Introduced limits: no protection for security bypass methods

7. Google LLC v. Oracle (Federal Circuit 2014 – earlier phase)

Facts:

• Federal Circuit initially ruled APIs ARE copyrightable

Holding (later reversed by Supreme Court):

• APIs are expressive and protected

Key Principle:

API declarations can be copyrighted, but subject to fair use defense.

Impact:

• Created legal uncertainty for API developers

4. Legal Principles Derived from Case Law

From these cases, U.S. law establishes:

(1) APIs may be partially copyrightable

• Code is protected
• Functional structure often is not

(2) Functional interfaces are NOT protected

(Lotus v. Borland principle)

(3) Reverse engineering is often allowed

(Sega, Sony cases)

(4) Fair use is the strongest defense in API disputes

(Oracle v. Google)

(5) Interoperability is a major policy consideration

Courts favor competition and compatibility

(6) BUT copying can still be infringement if:

• Literal code is copied
• No transformation exists
• Market harm is proven

5. Practical Legal Outcome in API Cloning Disputes

U.S. courts typically decide based on:

Allowed API cloning:

• Replicating endpoints for compatibility
• Recreating functional structure
• Reverse engineering for interoperability

Not allowed:

• Copying source code directly
• Copying proprietary implementation logic
• Copying documentation verbatim
• Circumventing technical protection systems illegally

6. Conclusion

API cloning disputes in the U.S. are governed by a balanced approach:

Copyright protects expression, not functionality—especially in software interfaces designed for interoperability.

The strongest modern precedent is:

• Oracle v. Google → APIs can be copied under fair use if transformative and interoperable

While earlier cases like Lotus v. Borland and Sega v. Accolade strongly support the idea that functional systems and reverse engineering are not infringing when done for compatibility.