Project Success Triangle - are all points really constrained?

Success for a Project Team is usually defined using the 3 points of the Project Success triangle i.e. Time, Cost and Quality/Scope. However, if, when establishing the Project Brief, it becomes clear from discussions with the Sponsor that he/she wants to constrain all three points before any Planning and Estimating has taken place, it could be time to find a way to exit the Project as per the cartoon :)

Joking aside, in such a circumstance (and in fact in all Projects) I ask the Sponsor the following questions, "Which is the most important point of constraint, which is second priority and which is the least important?". This might take a bit of probing with examples to illustrate but ultimately I have found that all Sponsors will give you this steer. 

Let me illustrate using the IT Product development example of the cartoon. After some discussions, it becomes clear that the Sponsor needs to get the Product into the market fast because of concerns of a competitor thinking about a similar product (Time top priority). Funds are tight but if there was some positive market feedback, more funds would become available (Cost second priority). So Quality/Scope is the least important constraint. So I might probe, "when we go live initially, could we possibly get the top 3 functions out and limit the user base to a 100 users or so?". If the Sponsor agrees to this as a possible approach we have teased out a much more useful Project Brief which will guide the Project Manager during Planning and Estimating which might lead to a Minimum Viable Product launch to a constrained user base with further releases and increased infrastructure to support more users (with additional funding) in future.

It is far better, ultimately, for the Sponsor, if you challenge the constraints and other Project Brief elements in early discussions rather than go away for 3 weeks and come back and tell him/her that the Project as requested can't be delivered or even worse, start the Project hoping for the best and fail.

So in summary I would say the main points I would recommend to Project Managers are:

1. If the Project Sponsor isn't clear, find one - see this article
2. Establish the Project Brief with the Sponsor to guide the Project Manager in Planning and Estimating
3. Part of this Brief should be the order of priority of each of the 3 points of the Project success triangle
4. Always look to have a discussion with the Sponsor even if you have been handed a solid written Brief (unlikely!)
5. Be prepared to challenge the Sponsor and probe as necessary, the first answer isn't always the correct one
6. As your "contract" with the Sponsor, is the Project Definition, all this information should be put into that document and signed off by the Sponsor or Project Board
7. If time is tight you may need to start work in parallel to agreeing the Project Definition and even scale your deliverables appropriately (I have agreed Project Briefs over email for example). As long as you make it clear any risks you are taking on behalf of the Sponsor this is fine in my view.