Annex A – Criminal Law and Procedure
The statutory provisions regulating time limits are contained in the Criminal Procedure (Scotland) Act 1995.
There are two types of criminal procedure – "solemn" and "summary". In summary procedure, a trial is held in the Sheriff or Justice of the Peace Court before a judge without a jury. In solemn procedure the trial, whether in the High Court or the Sheriff Court, is held before a judge sitting with a jury of 15 people.
Time limits apply in summary cases. In general statutory charges, that can be prosecuted in the summary courts only,  will time bar from six months from the date of the last mentioned offence.  In summary cases if a person is remanded in custody, the trial must commence within 40 days of first appearing in court. 
Solemn Proceedings generally commence with the accused person appearing in court "on petition" or being "placed on petition". The petition is the initiating warrant in such proceedings and sets out the nature of the criminal allegations (charges). When the accused first appears at court, the most likely outcome is that s/he will be "committed for further examination" ( CFE). The accused will then either be released on bail or remanded in custody pending trial.  If remanded in custody, the accused must be brought back to court within 8 days and then they will likely be "fully committed" ( FC) for trial. Time limits apply from the point at which the accused is either CFE'd on bail or FC in custody.  Time limits apply to every charge for each accused. Time limits for solemn cases are different for accused persons on bail and those who are remanded in custody.
If the accused is granted bail the first diet (Sheriff Court) or preliminary hearing (High Court) must commence within 11 months of CFE  and the trial diet within 12 months.  In bail cases the prosecution must serve an indictment – the document narrating the charges, witnesses and productions for the case – on the accused or their legal representative not less than 29 days prior to the first diet or preliminary hearing.  The purpose of the first diet or the preliminary hearing is to determine the state of preparation of the defence and the prosecution and ensure outstanding issues are resolved before trial.  The first diet in Sheriff and Jury proceedings must take place not less than 15 clear days after service of the indictment and not less than 10 clear days before any trial. 
If the accused is remanded in custody the prosecution must serve an indictment on the accused or their legal representative within 80 days of FC.  The Preliminary Hearing or First Diet must be held within 110 days of FC  and not less than 29 clear days after service of the indictment. The trial is fixed by the court at the Preliminary Hearing and must commence within 140 days of FC. 
Failure to adhere to any of these custody time limits results in the accused being granted bail and released from custody. 
Time limits in solemn custody cases run from the date of the FC, whereas time limits in bail cases run from the date of the CFE.
In all cases, if the 11 and 12 month bail time limits are not complied with, the proceedings come to an end and the accused can never be prosecuted on those charges. 
However, time limits can be extended in both bail and custody cases.  In any application for an extension, the test is whether the prosecution has shown sufficient cause to justify the extension sought. If the prosecution satisfies that test, the second stage is for the court to decide whether or not to exercise its discretion in favour of the prosecution in all the circumstances.  The prosecutor must therefore be prepared to address the court in detail on the procedural history of the case and provide a full explanation for the reason why an extension is necessary and why it is in the interests of justice that the application should be granted. The grant or refusal of any application for extension may be appealed to the High Court. 
A distinctive feature of Scots law is the requirement for corroboration of evidence in criminal cases.
Corroboration was described by Lord Carloway  as:
"There must first be at least one source of evidence ( i.e. the testimony of one witness) that points to the guilt of the accused as the perpetrator of the crime. That evidence may be direct  or circumstantial.  Secondly, each "essential" or "crucial" fact,  requiring to be proved, must be corroborated by other direct or circumstantial evidence ( i.e. the testimony of at least one other witness)."
Generally, there are two crucial facts requiring proof in every crime: (1) that the offence was committed; and (2) that the accused committed it.