How to break a patent claim into limitations
A step-by-step method for splitting a patent claim into labelled limitations, worked through on claim 1 of the expired 1-Click patent, US 5,960,411.
By the One Transform team7 min read
Split a claim at its natural joints. Separate the preamble, note the transitional phrase, give each element or step in the body its own row, and decide clause by clause whether a "wherein" or "whereby" clause adds a requirement of its own. Label every piece (1[pre], 1[a], 1[b]...) and quote it verbatim, so the claim chart, the construction brief and the expert report all point at the same words.
Why the split matters
Every later analysis inherits the split. Literal infringement requires every limitation to be present, and the doctrine of equivalents is applied to individual claim elements, not to the invention as a whole (Warner-Jenkinson Co. v. Hilton Davis Chemical Co., 520 U.S. 17 (1997)). Whatever you call "an element" becomes the unit that gets proven or attacked.
A split that is too coarse hides gaps: one row can be well supported for half its words and unsupported for the rest. A split that is too fine produces fragments that cannot be judged on their own. The target is one row per requirement that a product or reference could meet or miss independently. For what each column of the finished chart should hold, see how to read an element-by-element claim chart.
Step 1: separate the preamble
The preamble is everything before the transitional phrase. Give it its own label, 1[pre], even if you think it does not limit the claim.
Whether it limits is a construction question. A preamble is limiting when it recites essential structure or steps, when it gives life, meaning and vitality to the claim, or when it provides antecedent basis for terms in the body; otherwise it usually is not (MPEP 2111.02; Catalina Marketing International, Inc. v. Coolsavings.com, Inc., 289 F.3d 801 (Fed. Cir. 2002)). Charting it costs one row and saves an argument later about a row that is missing.
Step 2: find the transitional phrase
The transitional phrase sets how the claim treats anything the product has beyond what the claim recites. MPEP 2111.03 describes the three common forms.
| Phrase | Effect | What it means for the chart |
|---|---|---|
| comprising | Open-ended | Extra features in the product or reference do not take it outside the claim |
| consisting of | Closed | An unrecited component in the product needs its own note |
| consisting essentially of | Excludes elements that materially affect the basic and novel characteristics | You need a stated view of what those characteristics are |
The transitional phrase is not a limitation in itself, but keep it in the 1[pre] row so the reader sees it.
Step 3: split the body at each element or step
Semicolons and "and" are the drafter's hints, not rules. In a method claim, each step (a verb doing something to something) is usually a row. In an apparatus claim, each component and the relationships recited for it form a row. Keep modifiers with the words they modify, and keep every word: "only", "each", "at least some" and "all" often decide the case.
Step 4: decide what to do with wherein and whereby clauses
A "wherein" clause usually adds a requirement to something already recited: a property, a relationship, a condition. Give it its own label, or a sub-label such as 1[c][i], when a product could meet the main element and still miss the clause.
A "whereby" clause often describes the result of the steps already recited. Courts have generally given no weight to a whereby clause that only states the intended result of positively recited steps, but have treated one that is material to patentability, for example one relied on to distinguish prior art, as limiting. Chart it as its own row either way, and record which view you take and why.
Step 5: track antecedent basis
"A" or "an" introduces a term; "the" or "said" refers back to it. Build a term list as you split. Each later use should point to exactly one earlier introduction.
A term that refers back to nothing, or to two possible things, raises a definiteness question, because 35 U.S.C. § 112(b) requires claims that particularly point out and distinctly claim the subject matter. For the chart, antecedent basis decides whether the product must use the same thing in two rows or may use two different things.
Step 6: split nested limitations only where they can fail separately
Split a clause further when a product could plausibly satisfy one part and not the other. Keep it whole when the parts only make sense together. Two cases need care:
- Clauses that govern several steps. A phrase such as "under control of a client system" may apply to more than one step. Repeat it in each row it governs, or add a note to each row, rather than charting it once.
- Dependent claims. Under § 112(d), a dependent claim incorporates all the limitations of the claim it refers to. Label its added limitation 2[a] and record that claim 2 also carries every row of claim 1.
Worked example: claim 1 of US 5,960,411
US 5,960,411 A, "Method and system for placing a purchase order via a communications network" (the 1-Click patent), was filed on 12 September 1997, issued on 28 September 1999 and has expired. Here is claim 1, split.
| Label | Claim text |
|---|---|
| 1[pre] | A method of placing an order for an item comprising: |
| 1[a] | under control of a client system, displaying information identifying the item; and |
| 1[b][i] | in response to only a single action being performed, |
| 1[b][ii] | sending a request to order the item along with an identifier of a purchaser of the item to a server system; |
| 1[c] | under control of a single-action ordering component of the server system, receiving the request; |
| 1[d] | retrieving additional information previously stored for the purchaser identified by the identifier in the received request; and |
| 1[e] | generating an order to purchase the requested item for the purchaser identified by the identifier in the received request using the retrieved additional information; and |
| 1[f] | fulfilling the generated order to complete purchase of the item |
| 1[g] | whereby the item is ordered without using a shopping cart ordering model. |
Why 1[b] is split
A system could send a request that carries the item and a purchaser identifier while requiring two user actions to trigger it. That system meets 1[b][ii] and misses 1[b][i]. Splitting the row shows exactly where it fails. The word "only" belongs in 1[b][i] and should never be dropped from a quotation.
The "under control of" clauses
The punctuation suggests that "under control of a client system" governs both 1[a] and 1[b], and that "under control of a single-action ordering component of the server system" governs 1[c], 1[d] and 1[e]. Whether 1[f] sits under the server component is less clear. That is a construction question, so the chart should note the governing clause in each row rather than resolve it silently.
Antecedent basis
| Term | Introduced in | Referred back to in |
|---|---|---|
| the item | 1[pre] ("an item") | 1[a], 1[b][ii], 1[e], 1[f], 1[g] |
| a server system | 1[b][ii] | 1[c] |
| a request to order the item | 1[b][ii] | 1[c] ("the request"), 1[d] and 1[e] ("the received request") |
| a purchaser | 1[b][ii] | 1[d], 1[e] |
| an identifier | 1[b][ii] | 1[d], 1[e] ("the identifier") |
| additional information | 1[d] | 1[e] ("the retrieved additional information") |
| an order | 1[e] | 1[f] ("the generated order") |
The table shows how much depends on the preamble here: 1[pre] supplies "an item", which most of the later steps refer back to. That is one reason to chart the preamble even when you expect it to be read as non-limiting.
What the whereby clause adds
Clause 1[g] says the item is ordered without using a shopping cart ordering model. If the positively recited steps already mean that no cart is used for this order, the clause states their result and adds nothing to prove. It starts to matter in a harder case: a system that performs every step but places the item in a hidden cart and checks it out instantly. There, the whole dispute may sit in 1[g]. Check the prosecution history before deciding, because a whereby clause relied on to distinguish prior art is more likely to be treated as limiting.
Common mistakes
- Paraphrasing claim text in the limitation column instead of quoting it.
- Dropping small words such as "only", "each" and "at least some".
- Merging two requirements because the drafter put them in one clause.
- Charting a dependent claim without its parent's rows.
- Relabelling between the chart, the contentions and the expert report.
Try it
One Transform's Infringement search begins exactly here: it starts from your patent's claims and parses them into individual limitations, then searches product documentation, datasheets and technical literature for products that appear to implement them. Each candidate is charted limitation by limitation, with a finding of present, partially present or not found and evidence for every element. Compare its split with the steps above before you rely on the findings.
Next step: start an Infringement search from your own claims.
This article is general information about patent practice, not legal advice. For advice on a specific matter, consult a registered patent attorney or agent.
