The reason why marriage records like San Joaquin County Marriage Records are some of the most requested for records from the government would be because of the fact that these are the official records of the government in regards to the marriage of the person named in the record, and as such, these are the best evidence that one could provide in order to prove the fact of the marriage, something that is often necessary given that marriage is something that would have effects that would be binding upon the whole world because it is something that would change the status of the person named in the record.
Such change in status carries with it implications that would bind the whole world because status is something that would follow the person no matter where the person may go in his or her life. It is also something that would attach upon the person in question certain rights and privileges as well as limitations and duties that would also bind the person in question as well as the world no matter where the person in question may go. This is the reason why a person who is already married does not escape the fact of his or her marriage by simply fleeing to a different jurisdiction, and is the reason why a person who is not married could not get married again without first dissolving the first marriage.
As the official records of the government, these records are the best evidence that one could present in order to prove the fact of the marriage because these records are afforded the presumption of regularity, and that presumption works so as to exempt the party presenting the records from having to prove that the contents of the records are true and accurate, though it must be noted that the presumption works only if the records were obtained from the proper sources, thus, there is still the need to prove that the records were obtained from such sources. Note as well that the presumption is merely prima facie and may be overturned through the use of competent evidence to be presented by the party who would claim that the records are false.
A request for copies of the records could be done from a number of offices, though most requests are made at the local or county level as there would be fewer records here that would have to be checked, though it must be noted that there is a limit to the number of records that could be checked here because local level offices only keep copies of records for marriages that were celebrated within their jurisdiction, thus, it is possible that the record that is the target of the person making the request could not be found here.
San Joaquin County Vital Records may also be found online through the use of online databases, but it must be noted that these databases are not official sources for the presumption of regularity to apply to them. Still, they could present the information faster and more efficiently, and they are also easier to find and use.