From the Immigration rules, we can see that:
In addition to the grounds of refusal of entry clearance or leave to enter set out in Parts 2-8 of these Rules, and subject to paragraph 321 below, the following grounds for the refusal of entry clearance or leave to enter apply:
...save where the Immigration Officer is satisfied that admission would be justified for strong compassionate reasons, conviction in any country including the United Kingdom of an offence which, if committed in the United Kingdom, is punishable with imprisonment for a term of 12 months or any greater punishment or, if committed outside the United Kingdom, would be so punishable if the conduct constituting the offence had occurred in the United Kingdom (HC395, p320)
What this means is that if your fiance/spouse has been convicted for an offense that would have been punishable in the UK by a prison term of 12 months or more, then the application could be refused on these grounds. Whether a sentence was actually served or not is irrelevant to the decision.
Note also that the sentence actually received in the fiance/spouse's country is also not the deciding factor, but rather how the same offense would be handled by a UK court. The DSPs go on to say this...
Paragraph 320(18) of the Rules states that an application should normally be refused if that person has been convicted of an offence in any country which, if committed in the UK , would be punishable by imprisonment of 12 months or more. If you are not sure whether the offence would attract such a sentence, you should defer the application and seek advice from Policy Section, UKvisas.
If there are compassionate or exceptional circumstances involved, it may be possible for entry clearance to be issued on authority from the Home Office on a discretionary basis. Applications falling within this category should be referred to the ICD for a decision.
Finally, the ECO will consider any compassionate grounds offered and if these are compelling enough, the visa may still be issued. If you believe you have compassionate grounds, you would be well advised to consult a solicitor or adviser before filing the application.
Update 29 February 2012
The UKBA policy unit issued a communication, which contains this extract...
"...Cautions, reprimands and final warnings are not criminal convictions and so are not dealt with by the Act. So if people with cautions, reprimands or final warnings are only asked whether they have any 'criminal convictions' they can answer 'no'..."
Update 5 May 2012
In 2012, Parliament enacted sweeping changes to the UK legal environment in the Legal Aid, Sentencing and Punishment of Offenders Act. Of particular interest here is Section 140 of this Act, which is entitled, " No rehabilitation for certain immigration or nationality purposes" and this section states that an applicant can no longer rely upon the Rehabilitation of Offenders Act 1974 to avoid declaring previous convictions.
Note that this new legislation makes numerous advisories and commentary currently published on the internet obsolete. This includes any advisories that we (viz, Transpondia) authored.
Also among those published documents on the net which are obsolete are UKBA's Entry Clearance Guidelines. This was raised at a meeting with UKBA on 3 May 2012 where an urgent need for updated guidelines was expressed. We (i.e., Transpondia) will be working with UKBA in the coming weeks to put some shape on this problem. We'll put an update on this page when we know something concrete, but given the state of affairs that may be quite some time from now.
What should be done in the meantime? Section 140 has not yet commenced, so the first course of action is to watch for its commmencement. At that time (and in the absence of guidance), the only option is to list everything. And yes, everything means everything. If you omit something and later get caught, they can revoke your nationality and the courts are happy to support them in cases of deception.
ILPA's Parliamentary briefing: http://www.ilpa.org.uk/data/resources/14162/12.02.07-Briefing-on-Rehabilitation-of-Offenders.pdf
To follow up on this information, check our Internet Resources page...
Reviewed 9 May 2012