Depositions, either written or oral, have been a part of our legal system for hundreds of years. Traditionally, they are part of the "discovery" process, that phase of a lawsuit where the parties try to find out the opposing party's position and evidence. In many cases this process is more important than the trial or the decision in the case. Under the rules of procedure, any party to a lawsuit could solicit oral or written testimony from any witness or party to the lawsuit. Many this this testimony was recorded and made a part of the record of the entire court proceedings. In very early times, the statements were often referred to a affidavits or statements under oath. The evidence obtained by this method was often used to preserve the testimony of a dying witness or one that was moving away from the jurisdiction of the court. In some instances, the written record of the testimony given by the witness could be read into a later trial proceeding, just as if the witness had been present when the testimony was given.
From and genealogical standpoint, these depositions and affidavits may contain vital historically important information. Many times, the attorney taking the deposition would ask general questions of the witness concerning their relationship to the parties in the case and even their individual background, including schools attended, degrees received, family members, work history, where the witness was born and raised and other seemingly unrelated and personal questions. Reading such a deposition can be a window into the life of the deponent (person giving the deposition).
Sometimes, especially earlier in our history, all of this pre-trial discovery was preserved by the courts. Lately, the courts have refused to maintain all this information, but some of it is still preserved in the trial transcripts and notes in the court records. Finding an ancestor's court record can be extremely valuable. But it is sometimes worthwhile to pursue the search further and see if any of the law firms or lawyers who represented the parties in the lawsuit still have any of the documents from the lawsuits or if they were otherwise preserved in some repository with the attorney's papers.
Many times the testimony given at a deposition was formally recorded by a court reporter. In very early times, these records were made in longhand, but it became popular to take them down in shorthand and later transcribe the testimony. Some of these early court reporter's transcripts may also be preserved by the courts. Sometimes the record may also be maintained in the estate of the court reporter. It may take some real detective work to find these documents, but they may hold vital information concerning long dead controversies that have been obscured by the family memory.
Look for this kind of record in any court proceedings. If you find a record of a lawsuit, don't forget to ask if the court maintained any of the evidence from the trial or proceeding. Court transcripts of deposition testimony may be maintained separately from the formal record of the court case. Also pursue seeking both attorneys' and court reporters' records to see if any of them still exist. Both attorneys and court reporters are almost always identified by name somewhere in the court proceedings. Be careful to record this information for further investigation. This is one area where persistence and doing the work yourself will pay off.