Liability for Computer Errors

Not covered in textbook

Computer errors

• A range of possible consequences– Seconds lost– Data lost– $ - $$$– Injuries and deaths

• Examples:– Disfranchised voters– False arrests– Price & billing errors– Air traffic control, airplane control

Intrinsic & Extrinsic software

• Intrinsic:– Software that is part of a completed product

• Extrinsic:– Loaded onto the computer or machine of the user,

user directly encounters

The Therac-25 Case

• Radiation therapy machine• Typical system malfunctions number 40x day

The Therac-25 case cont’d

• 20 month period, overdoses to 6 patients, directly killing 3.

• Previous models, 6 & 20– Differences to the 25?

• Chronology of accidents– Please see

http://computingcases.org/case_materials/therac/supporting_docs/therac_case_narr/therac_toc.html

What was wrong with the Therac-25 programming?

• 2 modes– X-ray: high intensity beam deflected by tungsten target– Electron: removes tungsten & reduces beam intensity by

factor of 100• Quickly changing* (data entry editing) between mode

resulted in electron mode not dropping the beam intensity– * If the operator was able to edit and start < 8 seconds

• Use of a Race condition – 2 or more tasks sharing a variable, order that each is encountered can affect behavior of the program– The Therac-25 no longer had the hardware safety feature

Therac 25

• Problems– No fail safe– No dose reporting– Complicated programming– Re-use of code

• Who had moral and/or legal responsibility?– Harm shown– Was there intent? – Was there negligence?

• Define negligence

Extrinsic Software Failures

• With these examples, companies or individuals are buying software for what it can do for them.– Disclaiming liability for problems through

warranties

Software Warranties

• Limiting liability to:– A refund of the purchase price– Repair of the software product

• Accepting no liability for– Business losses arising out of the use of the

product• Enforceability of these disclaimers?– UCC & the Magnuson-Moss Warranty Act– Mix of case law

NCR’s Warehouse Manager• Warehouse Manager was an inventory

program. It was developed for a different operating system than it was deployed for.

• The “deadly embrace”• NCR continued selling it, claiming 200 successful

installs, but that was actually on other op sys.– When problems reported, told customers that was

“unique”

Extrinsic Business Software Failures

NCR cont’d

• Hopper bought the system. – Did not get honest disclosure from NCR. • NCR sold it to him after product had been discontinued.

– Errors about inventory and pricing resulted.• $114 item listed for 54 cents; $17 item listed as on sale

for $30.

– Hopper was operating a successful co., but after adoption of WM income was half. • Processes took to long & were inaccurate. Inventory

inaccuracies

NCR conclusion

• Hopper tried to sue NCR for $4.2 million.• However, the sales agreement signed by

Hopper stated that in the event of problems, NCR was only responsible for the original cost of the software minus the depreciation of the equipment.

• The agreement also had an arbitration clause, so the court refused the case.

ProCD v. Zeidenberg

• ProCD selling mailing list generating software– 2 prices, 1 for personal 1 for business

• Zeidenberg bought it as personal and created a mailing list sales business using the product.

• ProCD sued saying this violated terms of the license• Terms not found on box but on click thru agmt

• Ct found that Zeidenberg could be held to those terms of the click through agreement and was in violation of the software license.

Mortenson v. Timberline Software

• Precison Bid software• Used it and created bid $1.95 million too low• Licensing disclaimed business losses related to

use of the software in excess of licensing fee• Timberline was aware of bug, did not send fix

to Mortenson.• Ct. found the Timberline was not liable b/c

licensing agmt. properly limited liability.