Python style: exceptions vs. sys.exit()

Steven D'Aprano steve at
Sat Oct 4 05:40:14 CEST 2008

On Fri, 03 Oct 2008 09:15:35 -0500, Grant Edwards wrote:

> On 2008-10-03, greg <greg at> wrote:
>> Lawrence D'Oliveiro wrote:
>>> In message <00f15d41$0$20617$c3e8da3 at>, Steven
>>> D'Aprano wrote:
>>> > (2) Even when the source is available, it is sometimes a legal trap
>>> > to read it with respect to patents and copyright.
>>> That's not how patents work.
>> I don't think that's how copyrights work either. As far as I know,
>> whether something is deemed a derivative work is judged on the basis of
>> how similar it is to another work, not whether its author had knowledge
>> of the other work. As long as you express an idea in an original way,
>> it shouldn't matter where you got the idea from.
> IANAL, but IIRC it does matter when it comes to establishing punative
> damages.  If you knowingly and intentionally infringe a patent, I think
> you're libel for more damages than if you accidentally re-invent
> something.  At least that's what I was told...

Yes. Under US Patent Law, if you intentionally infringe a patent you are 
liable (not libel, which is like slander) to triple damages. 
Unfortunately the meaning of "intentionally" is horribly broad: if you do 
a patent search and find a patent which you don't think covers your 
invention, but a court later decides that it does, that counts as 
intentional infringement. But if you don't do a patent search at all, any 
such infringement must be accidental.

Yes, this is incredibly broken. Economists and lawyers call it a 
"perverse incentive":

"Finally, the provision for treble damages for willful infringement 
actually creates a perverse incentive not to know about patents that 
might be infringed. If a search is undertaken and knowledge of potential 
infringement is obtained, then the willfulness provision will be 
triggered and the infringer may be liable for treble damages. On the 
other hand, without a search there can be no knowledge, and no willful 

Under Germany patent law, there is no difference in damages for 
intentional, negligent or accidental infringement, hence no punitive 
damages and no triple punishment for doing a patent search:


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