Why Do Patents Have Dependent Claims?

[Mech King]

I know that the interpretation of patent claims can be a complex art, but can you help me clarify some logic:

Basically, if your design differs from someones independent patent claim, with the exclusion of one element, then it will not be infringing that patent. So if you don't infringe any indepent claims of the patent then you do not infringe at all.

But my main query is, what is then the point of having independent claims to further define the elements of the design? Because shorley if you don't infinge the independent claims then the dependent ones are irrelevent?

But if you have all the elements listed in the independent claim then only then will a dependent claim be applicable - if you infringe the claim that it is independent on.

So to that end why do they bother with dependent claims?

Anybody have any clues?

Many Thanks

Mech King

 

[getitright]

The difference in the two patents must demonstrate a 'substantial' change in the 'use or purpose' of the item. The court then walks the fine line between supporting 'what is' and 'what could be' and determining if there is a distinction between the two in the case before the court.

 

[Mech King]

I understand the legal process, but I am facing a dillema as to what the what is the significance of the dependent claims?

If you don't infringe the independent claims then how can you infring the the dependent claims that depend upon that independent claim?

 

[mgb_phys]

So to that end why do they bother with dependent claims?

Generally because you only have to infringe one of the claims to be sued.

So in a patent you will first claim some over-arching invention (like the wheel) and then a bunch of dependent sub-claims about particular implementations.
That's why you get language such as "the invention where the surface of the wheel is substantially round"
Generally the overarching invention gets thrown out as obvious or too general and you win on one of the minor implementation claims.

You could also file separate patents on each of the sub claims but that is a lot more money/work.

The famous one is Edison and movie film, his claim to have invented it was thrown out but one of the sub-claims was to use sprocket holes which stood an gave him an monopoly.

 

[Mech King]

Thanks mgb_phys,

but what if your invention is different from the main overarching independent claim, but you totally infringe one of the dependent claims? Would this mean you would not be sued because the claim you have infringed is dependent upon the first independent claim? If that makes sense.

So if one deosn't infringe the independent claim 1 (for example), then any claim independent on claim 1 cannot be infringed?

 

[mgb_phys]

No the whole point is that the claims standalone
The main claim almost never stands, you get people on the dependent claims

It's tricky because it's not a question of if you violated the claims, it's a question of will the court decide you have. Or these days more a question of can the other guy keep you in court long enough that you go bust before they do.
The normal advice is to ask a lawyer/patent agent - in my experience all they do is send you a list of patents that you violate, which when you look at them suggests that some office junior just put all the keywords into google.

 

[Mech King]

Thanks mgb_phys,

I have heard contrasting things in the past and to be honest its such a minefield, that you just never feel totally secure unless youknow your invention is totally 100% unique.

thanks for your comments,

cheers

 

[mgb_phys]

to be honest its such a minefield,

That's lawyers for you.
I worked for companies that filed lots of patents. Essentially we use them as NDAs, before a meeting with a client you file a patent on absolutely anything you can think of on that topic. Then if there is an argument about something - you can claim to already have invented it - none of these patents would ever have stood upto anything.
We were also advised both to NEVER do a patent search on anything we worked on - because if we could be shown to have known about a patent that could be used in court to show intent, we were separately advised that if we DIDN'T do a patent search then we were committing perjury when we file a patent because we din't show due dilligence

that you just never feel totally secure unless youknow your invention is totally 100% unique.

I think that went out of thew window 100years ago. Patents are now on things the process of like comparing prices and buying the cheapest!
IBM is even trying to patent using patents against competitors!

 

[Mech King]

what a crazy world eh?

:)