Q:

Is it OK to lie to a customer to protect them from themselves?

I'm a software developer.
A part of the application I'm currently working on is distributing big amounts of money to the clients of my customer.
In the application the users – employees of my customer – have to decide and choose which client gets a certain amount.
Based on the information in the system the application could make an educated guess which client is the correct one. But as the information might be wrong or incorrect I can't be 100% certain.
Now the customer has requested to preselect the most probable client, so the user only has to click OK, instead of selecting the client first, if the application guessed correctly.
I fear that, if I implement this, some users would always just click OK, instead of thinking whether the selected client is correct or not. Which would lead to thousands of Euros transferred to the wrong clients.
Knowing my customer, he won't listen to my argument. 
So my only options are implementing this possibly harmful change, or lying to the customer, telling him, that this is technically impossible.
Is it professional/ethical to lie to a customer to protect them from harming themselves, if they don't listen to an argument, in this or other scenarios?

A:

You should never lie to a customer. For that matter it is generally not a good idea to lie to anyone but that is a broader ethical issue for further consideration in a different venue.
Trying to say that it is "impossible for the programming" to make the likely choice guess would stand out as so obviously wrong that you should not even go there. If the customer can surmise the scenario from the data at hand then it is possible for a program to be written to come to the same conclusions. 
In my work when I encounter similar situations I will normally implement what the customer desires but will also help them see that there may need to be additional steps taken to reduce mistakes. In this scenario the customer is suggesting something that will improve work flow productivity. This can help save time pawing through a customer list dialog to manually select the specific one. On the other hand once the commit is made to post the transaction the programming could note that the auto filled field choice has been used and that the amount total is large and then pop up an "are you sure" confirmation that shows pertinent data. A quick click of confirmation hardly interrupts the work flow at all.
So in conclusion - work with the customer to find good solutions instead of trying to make your own judgements of what is right or wrong with their ideas.

A:

It's not professional to lie to your client to protect them from harming themselves. Your client is not a child, they are an adult and are expected to be allowed to make their own decisions in life. Including ones that will cost them reputation, money, or their company.
Think about it if it were professional/ethical to do this. Would you want your doctor to lie to you about the risks of smoking to "protect you from yourself"? Would you want your mechanic to lie to you about the risks of not fixing your broken watchamacallit to "protect you from yourself"?
I think you would want it to be your own, informed decision. And I think your client will want the same.

A:

The professionally/ethically correct way of doing this would be to accurately inform your customer about all risks. Then let him or her weight these risks and let them make an informed decision. You are not in the business of making risk assessments or business decisions. That's their job. You don't want them to tell you how to program, don't tell them how to do their job either.
Prepare a statement where it it clear that you see that risk, in simple terms so they can understand it. If you want to underline the importance of this risk, you can try to make them sign off on it. Have them write something like "I read and understood this risk, I want it implemented anyway." 
If the only risk is the business losing money, then this is all you can or should do. It's probably a whole different can of worms if the business owner is risking something that does not belong to him (for example client's health), but that is a different question and should go to a legal professional.

