Culpatic programming

In the legal world, there is this latin term ”culpa”, which translates
roughly to ”carelessness” or ”neglience”. The term does not seem to be
used in US Law, but I’m guessing a similar concept still exists in all
Common Law countries (it might be worth mentioning to the casual
Google refereant that this post is written based in my understanding
of swedish law — if you’re in some other jurisdiction you
should take this with an even larger grain of salt).

The concept of culpa, or rather careless behaviour, is very important
when it comes to assessing whether a certain harmful action (or
sometimes inaction) by a person should make that person liable for
damages. The rules differ somewhat if the two parties were in a legal
agreement of some kind, but basically — if you cause harmful effects,
you’re generally worse off if it was due to carelessness than if it
was by accident (”casus”).

For example, if a supplier did not deliver his goods to the customer
at the agreed time and place, and this was harmful to the customer in
some way, the supplier is more likely to be liable for damages if the
reason for the failed delivery was due to him forgetting about it, as
opposed to there being a unforeseeable traffic jam that prevented him
from reaching the delivery place on time.

To determine wheter a particular action should be categorized as casus
or culpa, a court need to have some sort of guideline as to what is
generally considered to be careless in the context of the harmful
action. In some cases (such as traffic, or working environments), there
are rules that more or less spell out what is considered careless. In
the absence of those rules, courts generally observe what level of
carefulness that is considered adequate by those proficient in the
profession or trade.

In the programming world, there’s a whole lot of ”culpatic
programming” going on — proficient developers know about appropriate
steps to ensure at least some level of quality in their delivered
products, ranging from design methologies to source code management to
customer involvement to established QA techniques. They also know that
these steps often are not followed — for whatever reason. The result
is buggy software that cost time, money and sometimes lives.

Yet, the fact that many programs and systems are carelessly written
ise rarely discussed — most of the time, it is observed that bugs
will happen, a EULA or
other agreement that absolves the company of liabilities due to bugs
in the code is slapped on, and that’s the end of that.

While is true that it’s impossible (in any practical sense) to write
bug-free programs, it is possible to make a meaningful
distinction between bugs cased by carelessness (”culpa” bugs) and bugs
cased by accident (”casus” bugs). The intented usage for the system
will probably affect how the distinction is made (a off-by-one bug
might well be determined to be a ”casus” bug in a admin UI for a
in-house CMS, but is probably a ”culpa” bug in the firmware for a
electronic pacemaker). This also means that software that, when
written, is likely to capture a mass market (such as the RPC server in
the next Windows version) could and should be held to a higher
standard than software written on a hobby basis, when it comes to
determine carelessness.

Often, when the issue of software liability is raised, the
discussion is cut short by the observation that software will always
have bug, and that some of them will cause disastrous effect. It’s
also observed that there is a point in software development where the
cost of finding and fixing the remaining bugs is larger than what the
customers are prepared to pay, and if we make the law demand software
developer liability, no programs (particularly open source ones) will
get released. While it’s true, it’s a all-or-nothing argument. As a
(semi-retired) developer, I’ve caused my fair share of bugs in my
time. Many of these were casus bugs, but some were culpa bugs, bugs
that I would not have created had I followed adequate development
procedures. It’s the latter sort of bug I’m talking about — the ones
that are technologically AND economically feasible to eliminate, but
developers lack incentive to do so (other than pride of

One large problem is that very few are qualified to determine
whether a bug is culpa or casus. Then again, very few are qualified to
determine if a certain food handling procedure is adequate or
neglient, or wheter a car’s failing braking system was carelessly
designed or not. The legal system still demands that we make a
destinction between culpa and casus in these cases, and does not allow
the food or car industry to sell their products with attached general
disclaimers that frees them from responsibility. Wheter enough care
was taken is determined by experts in the respective fields. For the
software case, this will mean letting independent parties review the
code and particular the conditions of the bug. This will, in many
cases, be expensive, but so are the problems that software bugs