Mr Justice Arnold finds American Science's mobile X-ray scanner patent valid

On Tuesday, the latest decision from Mr Justice Arnold in American Science & Engineering Inc v Rapiscan Systems Limited [2016] EWHC 756 was handed down.  Mr Justice Arnold upheld the patentee's invention relating to a covert mobile X-ray security scanning system as valid.  Before opening the decision, the AmeriKat thought that she would be in for the trade mark detailed, fully-explained decision that makes Arnold J's decisions excellent reading.  However, she was wrong.  The decision from Mr Justice Arnold was incredibly succinct - there wasn't a summary of the legal principles that were applied or reference to a single case because, as Mr Justice Arnold says, it was agreed between the parties and he has already set them out in "numerous previous judgments".  This made it a luxuriously easy decision for the AmeriKat to quickly summarize ["Purrrrr....."].

What is the patent?

American Science & Engineering (AS&E)'s patent EP (UK) No 1 558 947 entitled "X-ray backscatter mobile inspection van".  Backscatter X-ray, a category of Compton scattering (also known, as inelastic or non-classical scattering), is where photons scatter back from the matter with which they have interacted at about 180 degrees from the direction of the incident beam.  A photo of a backscatter X-ray image, as opposed to a transmission (dual energy) X-ray image, is set out below.    The priority date of the patent is 6 November 2002.   The invention has particular application in the security scanning market (i.e. airport security for detecting concealed devices in airline cargo).  AS&E's ZBV vehicles implement the claimed invention.

Why the dispute?

AS&E argued that Rapiscan infringed the patent.  During trial Rapiscan admitted it had committed the acts, but that the patent was invalid.  Rapiscan argued that the patent was obvious on the basis of a paper by Roderick Swift entitled "Mobile X-ray Backscatter Imaging System for Inspection of Vehicles" published on 19-20 November 1996 in the Proceedings of the SPIE conference ("Swift").  The Swift article introduces AS&E's MobileSearch system, which at that time was a prototype, and provides background for AS&E's earlier CargoSearch system (a system for inspecting vehicles crossing the border from Mexico to the US). CargoSearch was a mixed transmission and backscatter system. The vehicle or target was then towed slowly through the scanning area at a fixed speed. MobileSearch was a combined backscatter and transmission system (Swift explains that the prototype was designed only to include backscatter but could be upgraded to provide transmission imaging). Swift describes the objective of the prototype of being a fully mobile, self contained large-scale system. The occupants of scanned vehicles are required to exit before a scan is started. This very much removes the "covert" element needed to tackle security threats.

The common general knowledge

The SAIC VACIS range of vehicle and cargo inspection
systems where the truck is driven past a stationary target
(i.e. "drive-by" mode)

There was a lot of technical background, almost half a judgment's worth, which the AmeriKat recommends you read if interested.  All of the technical background was held to be part of the skilled person's CGK.  There was a dispute as to the extent to which knowledge of various commercial security imaging systems formed part of the skilled person's CGK.   The judge held that it was CGK that one of the commercially available systems, SAIC's VACIS system, was capable of being operated in a stationary mode and was equipped with a Doppler relative motion sensor to measure the speed of the target and to correct the aspect ratio in that mode.  However, the judge was not prepared to accept that it was CGK that it was actually being used in that mode.

What is the inventive concept?

Mr Justice Arnold accepted AS&E's submission of the inventive concept as being the following:

"The combination of (i) a vehicle containing a flying spot X-ray source and a backscatter detector, (ii) the source and the detector being entirely enclosed within the body of the vehicle when the vehicle is in motion during the course of an inspection and (iii) a relative motion sensor generating a signal based on the relative motion of the vehicle and the inspected object (thus enabling the aspect ratio of the image to be corrected)."

This combination enables a mobile X-ray scanner to be used for convert imaging three modes - drive-by (the scanner moving past the target), drive past (the target moving past the scanner) or when the target and scanner are both in motion.  This tri-modality is advantageous.

AS&E's ZBV vehicle - no boom, no detection....

What is the difference between the prior art and claim 1?

It was common ground that Swift disclosed most of the features of Claim 1, but not (g) being:

"characterised in that the system further comprises a relative motion sensor for generating a relative motion signal based on a relative motion of the enclosed conveyance and the inspected object."

 There was a dispute about whether Swift disclosed feature (f), being:

"the detector module is contained entirely within the body of the enclosed conveyance while the conveyance is in motion during the course of inspection"

The specification at [0021] make clear that the purpose of this feature was to ensure that the detectors are "concealed from view".  Swift referred to the doors as being "opened and secured" during scanning. Arnold J agreed with this position, holding that Swift did not disclose feature (f).

The judge held that, in so far as feature (f) was concerned, it was not obvious to re-design the system in Swift to operate with the doors shut.  The expert evidence before the judge indicated that to do so would require that the doors are replaced with non-attenuating material in order to obtain a useful image (it was not just a matter of closing the doors).  There was no motivating suggestion in Swift to convert Swift into a covert system.  Further, there were no covert X-ray imaging systems in operation (whether backscatter or transmission) at the priority date. Changing the Swift system to a covert system required hindsight.   Although a throwaway suggestion to that effect was made in passing by AS&E in a Port Technology International (a widely read industry journal) article, the judge did not consider that that changed his view as the article did not address the practicalities of the conversion. Feature (f) was not obvious.

The judge held that feature (g) was also not obvious.  The question of whether it was obvious to incorporate a relative motion sensor is predicated on whether it was obvious to turn Swift into a drive-past system.  It was not obvious to turn Swift into a drive-past system.   Swift did not mention the possibility of a drive-past mode. Its disclosure actually taught away from a drive-past mode as the Swift system requires that the driver of the target vehicle  leave the vehicle before scanning.  Indeed, Swift did not indicate that higher speeds could be used.  Instead it suggested that even at 1/2km/hr, the image starts to degrade.   For Swift to be converted to a drive-past system, the skilled team would be envisaging speeds more than 10 times faster, which Swift suggested was impractical.   Rapiscan's argument that it was obvious to convert Swift into a drive-past system was, again, tainted by hindsight

Merpel has nothing to hide, or
does she....?

The judge further held that the combination of features (f) and (g) were not obvious.  He held:

"... to arrive at the combination, the skilled person would have to conceive of making a mobile, covert, backscatter-only system which could operate in drive-past mode and incorporated a relative motion sensor for that purpose, despite the fact that Swift contains no hint of either covert or drive-past operation and indeed teaches away from both. It is only with hindsight that it can be seen that the necessary changes were relatively simple ones."

Mr Justice Arnold also commented that there were plenty of obvious paths to pursue on the basis of Swift which did not involve a change to the whole method of operation of the system (i.e. drive-past).

The age old question:  If it was obvious, why was it not done before?

With all the components necessary to make a system falling within the claim, AS&E asked the standard question of "if the invention was obvious, why was it not done before?"  Rapiscan said that it was not done before because AS&E had patent protection for X-ray backscatter systems and the burden was on AS&E to show this was not the case.  Mr Justice Arnold commented:

"I regard that as an extraordinary submission. In my judgment it is plain that, where a party which is attacking the validity of a patent on the grounds of obviousness wishes to rely upon a fact as explaining why the invention was not made before the patent, whether that fact relates to the availability of raw materials or a regulatory restriction or a commercial factor or the existence of an earlier patent owned by the patentee or a third party, then the burden of proving the existence and relevance of that fact lies upon that party. Furthermore, in the present case, not only was the suggestion unsupported by any evidence from Dr Lanza, but also when counsel for Rapiscan put the suggestion to Dr Bjorkholm in cross-examination, his evidence was that AS&E had no relevant patent protection. Accordingly, even if the burden lay upon AS&E to prove the negative, AS&E has discharged that burden."

The judge concluded that the fact that no-one had come up with the invention for the six-years between the publication of Swift and the priority date provided "modest support" for Claim 1 not being obvious.  He further concluded that Rapiscan's reaction to the invention, by designing and marketing a backscatter van, was prompted by the commercial success of AS&E's invention also provided "modest support" that Claim 1 is not obvious.