Ars covered the grant of Amazon's controversial patent last month. This guest post is by Charles Duan , director of the Patent Reform Project at Public Knowledge . It's an essay meant to answer a question frequently asked on Ars: how do bad patents get issued in the first place?

I. The problem

The patent examiner sat down at her desk and pulled up the next item on her examination docket. Patent application 13/292,359. "Studio Arrangement."

"Right in my area," she thought. She scanned the patent application text and flipped through the drawings. It seemed straightforward—a camera, a platform for holding an object, a couple of lamps, a backdrop. She’d seen all of this before.

She typed in a few search terms, looking for the prior art that would show this invention to be old and well-known. She browsed through a few old patents. Something triggered a vague memory of an old application she had examined years ago. Bits and pieces surfaced in her mind—a name here, a classification number there. She knew that she could find it, and after half an hour she did.

"Bingo!" she thought, placing the drawings from the old application next to the Studio Arrangement figures. Everything was lining up nicely. She began comparing the parts of each document, building up the legal argument that this arrangement of lamps and backgrounds could not be patented.

But then something caught her eye. A small sentence at the bottom of a page. Twenty-five words.

And those twenty-five words told her immediately that she could not reject the application over the prior art she found. She probably could not reject the application over any prior art she found.

She would have to grant the patent.

You already know how this story ends: Amazon gets U.S. Patent No. 8,676,045 on taking a photograph of an object in front of a white background. The headline “Amazon Patents White-Background Photography” is all over the Internet , with people exasperated that a decades-old technique could become the subject matter of a patent in 2014.

How did this patent make it through examination?

Some have suggested that it slipped through the cracks, that the examiner was asleep at the wheel, or that the Patent Office is a rubber stamp that grants all applications that come in the door. I doubt that any of these is the case. As a patent attorney, I saw plenty of applications rejected, saw examiners finding remarkable prior art, and still saw plenty of patents issued on the most obvious ideas.

The problem is not with the examiners, but with the law that governs that examination. That law makes it possible to get patents on ideas that any ordinary person would find old, well-known, and obvious.

This is a dramatization of how the patent came to be. Of course I was not in the room with the engineers, the patent attorneys, or the patent examiner; I don’t know them and have no relationship with them. But I do have the public record of the documents filed with the Patent Office, the audit trails of the searches conducted by the examiner, and the correspondence between the examiner and the patent attorneys. This allows me to reconstruct the story of the patent.

Although the narrative is fiction, the background of law and facts is accurate. My hope is that, by injecting these bare facts with the probable thoughts of the people involved, a complete story will emerge to explain this patent.

We started with the end of the story, just as the patent was about to be granted. So let’s jump back in time to the beginning, when the patent was just an idea in the inventors’ minds.

II. Ideas

“What’s new in the world of inventions?” the patent law firm partner asked as he sat down at the conference table, across from the three engineers. The group met once every few months to collect any new ideas out of the R&D department and to pick some to turn into patents.

“Well,” one of them said, “I don’t know what you’ll make of this, but we did come up with an interesting way to take pictures of products for our website.”

“Sure, go on,” said the partner, listening carefully.

"Basically, what usually happens is that we take a picture of a product, and then it’s got shadows or the background is a little off color or something, and you have to do some retouching or Photoshopping to fix it up before you put it online. And that’s kind of a pain. So we came up with this way of arranging things so that the background comes out completely white."

The engineer pulled out a few sketches. He walked the partner through them, and then asked one final question.

"So can we actually get a patent on this?"

The partner stopped to think for a second. "It depends really on what’s out there already. You don’t know if anyone has done something like this before, right?"

"Well of course people have taken pictures of things in front of a background before," said the engineer. "But everything we know of requires us to do some retouching afterwards. This is the first time we’ve set it up so we don’t need to do the retouching."

"In that case, it’s up to the patent examiner to find out if there is any prior art. There’s really no harm in trying."

The engineer nodded in agreement, and the partner extended his arm for a handshake. "You’ll have a draft by the end of the month."

Patents are intimately tied with inventions. Patents are meant for the great advances in technology that change industries or lives. When we think of patents, we think of things like the lightbulb, the airplane, and the automobile.

Criticized patents tend to be those granted on simple ideas that anyone with an ounce of skill could have come up with in the right situation. One-click shopping, Internet gambling, scanning documents to e-mail—these are all actual patents that have been derided for being too elementary and thus unworthy of patenting.

This intuition of “worthiness” of patents is known in legal parlance as obviousness. This is the central question in the debate over the Studio Arrangement patent. Most people have complained that photography against a white background is taught in every photography textbook, rendering the patent obvious. Others believe that the patent actually covers a unique way of arranging objects, thus making the patent nonobvious.

The Patent Office issued the patent, which means they thought there was something nonobvious about it. But what? To answer that, let’s see how the idea from the client meeting turns into a written patent application.

III. Claims

"So what do you have for me today?" The partner swiveled around in his chair to face the young associate closing the door to the office.

"It’s the studio arrangement patent application," the associate said, shuffling through a stack of paper.

“Studio arrangement?” The partner was shuffling through his memory of the other matters from the month.

“We had the client meeting a few weeks ago? It was the one where they had the white background, and the lamps, and—”

“Oh, that one!” The partner took the stack of paper and thumbed through the draft patent application. “Looks great so far—what about the claims?”

“Right here,” said the associate, pulling up the last page. Different from the narrative paragraphs of the rest of the application, the claim looked like a bullet point list, but without the bullets:

Claim 2. A studio arrangement, comprising: a background comprising a cyclorama; a front light source positioned in a longitudinal axis intersecting the background, the longitudinal axis further being substantially perpendicular to a surface of the background; an image capture position located between the background and the front light source in the longitudinal axis; an elevated platform positioned at a first distance from the elevated platform and between the image capture position and the background along the longitudinal axis, the front light source being directed toward the elevated platform; and at least one rear light source positioned between the elevated platform and the background, the at least one rear light source directed towards the background; wherein a top surface of the elevated platform reflects light emanating from the background such that the elevated platform appears a substantially similar color as the background and a rear edge of the elevated platform is substantially imperceptible to an image capture device positioned at the image capture position.

“It’s all here,” the associate continued. “We’ve got the white background here, the lamps here and here, the camera here, and the transparent platform here,” he said, pointing to various parts of the claim.

“And these are all the important features that those engineers talked about?”

“Yep, I’m pretty sure of it. They said that the key to the invention was that the object’s stand appeared invisible to the camera, so no retouching was necessary. And that last bit of the claim, where it says ‘the elevated platform appears a substantially similar color as the background,’ that’s where I put that feature.”

The partner looked up from the paper. “Looks like we’re in good shape,” he said. “Add a few dependent claims to fill things out, and we’ll send it out to the client by the end of the week.”

Claims are the legally operative part of a patent. They are structured like a checklist, and each item of that checklist is called an “element” or “limitation.” Claim 2 from above has elements such as the background, the front light source, the image capture source, and so on.

And claims act much like a checklist: to prove that something infringes a claim, one must prove that the thing includes every element of the claim.

(In case you’re wondering about claim 1: that claim has a longer list of elements than claim 2, and examiners usually start by looking at the shortest claim first, which is why I do the same here.)

The claims also determine obviousness. To prove obviousness, one would have to show that every element of the claim would have been obvious to someone familiar with the general field of technology. This is precisely what the patent examiner is going to do once the application is filed: she will search for prior art for all the elements of the claim.

But before she does that, before she even receives the patent application, our associate must complete one final task: adding dependent claims to the application.