If the McCanns did end up at the ECHR what might they achieve? Monetary awards are most often between 1,000 and 8,000 Euros. It can't overturn a decision, but it can order a retrial (please, no!) sometimes.
If the Court finds that there has been a violation, it may award you
“just satisfaction”, a sum of money in compensation for certain
forms of damage. The Court may also require the State concerned
to refund the expenses you have incurred in presenting your case.
If the Court finds that there has been no violation, you will not
have to pay any additional costs (such as those incurred by the
respondent State).
Please note:
" The Court is not empowered to overrule national decisions
or annul national laws.
" The Court is not responsible for the execution of its judgments.
As soon as it has given judgment, responsibility passes to
the Committee of Ministers3 of the Council of Europe, which
has the task of supervising execution and ensuring that any
compensation is paid.
The Court does not act as a court of appeal in relation to national
courts; it does not rehear cases, it cannot quash, vary or revise
their decisions.
" The Court will not intercede directly on your behalf with
the authority you are complaining about. In exceptional
circumstances the Court may, however, grant interim measures.
As a matter of practice it only does so where there is a serious
risk of physical harm to the applicant
http://www.echr.coe.int/Pages/home.aspx?p=applicants