It is often important to check the dates and timings of Tribunal judgements. Outwardly useful and helpful judgements can often relate to law that has since been revised. The reason is the 'absolute whirlwind' of legislative changes (Lord Hope's comments in Alvi) that take effect in Immigration law, the Immigration Rules being amended on almost a monthly basis, with little notice. Ironically enough, the Home Secretary's response to losing in Alvi was to enact more changes to the rules!
One example is the recent decision of Rodriguez (Flexibility Policy)  UKUT 00042 (IAC). A very useful judgement and extremely important for many appellants. It finally clarified the position of UKBA's secret 'Evidential Flexibility Policy', which was applied seemingly at the whim of a caseworker, and not even admitted to until it was discovered by a Freedom of Information Request.
Mr Justice McCloskey and Upper Tribunal Judge Spencer were critical of UKBA, in particular the respondent did not even furnish the tribunal with a copy of the policy and they had to dig it out themselves.
The judgement directs that a failure to apply this policy in respect of an application will potentially render a consequent decision to refuse leave unlawful. Very useful, although who knows how many people will have been refused and perhaps given up plans to study or work here, returning home without even knowing that someone else in an identical position might have been called by UKBA asking for a missing item.
The sting in the tail, as the tribunal comments on at paragraph 25, is that by September 2012 the Secretary of State had issued a further change to the Immigration Rules by way of Statement of Changes HC565. This actually incorporates some aspects of the policy into the rules. The Tribunal did not consider this issue, because the changes post date the facts in the appeal, but nevertheless the changes will be relevant for most individuals seeking to rely on the judgement, if their original application was made after 6th September 2012 (the judgement was promulgated on 7th January 2013).
This is actually a common issue. The Tribunal provides helpful guidance on an issue, but its rendered almost immediately out of date by another change. PBS cases especially suffer from this, such as CDS Brazil (still useful, but the rules had changed by the time it was promulgated).
In terms of Rodriguez it is unclear what the position would be at the moment. There is no explicit indication that the Flexibility Policy has been withdrawn and now there are rules which reflect some of that policy but are significantly more restrictive. It would not be the first time in which policy and rules have co-existed (see OS (10 years' lawful residence) Hong Kong  UKAIT 00031).
Notably, the Statement of Changes itself is silent on this point, not even really referring to the changes or their import, so plenty of room for debate about this.
Certainly until UKBA state that the policy is no more then both can exist at the same time and there is still scope to argue the policy should still be applied. Nice and simple then with no room for confusion....