There are 300 million smartphone users in the United States alone. Text messaging is part of virtually every adult's daily life. Because so much information is shared by text message, these messages can be critical evidence in lawsuits, including family law cases.
Written evidence has to be produced in a format that can be read by the judge and preserved by the court reporter. This means it is not enough to have your phone at the trial if you want to show a text message. You must have the text messages printed out or in a PDF file that can be stored on a USB flash drive (or both).
It is relatively easy on most cell phones to take a screenshot of anything appearing on the screen. However, this is one of the least desirable ways to share your text message evidence. Screenshots from some cell phones are very low resolution, which means that when the texts are printed on paper they are so grainy that they are illegible. Screenshots are also limited to what you can see on the screen, so you can only see a few messages for any given screenshot. Text messages require so much context that many times the meaning of the texts in a screenshot cannot be fully understood from the screenshot alone. So you need to be able to produce all the text messages in a format that is easily readible and understood.
There are basically two types of cell phones: Androids and iPhones. Text messages on Androids can often be exported to PDF format using a relatively cheap application called Legal Text Collector. Text messages on iPhones may be exported to PDF using iExplorer, which costs much more than the Android option.
Exporting the text messages is the first step, not the only step. Sometimes the other side will try to deny that the texts are authentic or legitimate. You will need to disclose the texts messages to the other side as soon as possible, because if you wait till the last minute there is a rule of evidence which allows evidence to be excluded if it is being used as part of an unfair surprise. With careful planning, you may be able to use the discovery process to force the other side to either admit that your texts are real or to show any evidence that they have supporting their claim that the texts are less than genuine.
If you only use screenshots, your attorney may have a difficult time properly arranging the screenshots in chronological order, and your use of screenshots may help the other side claim that the screenshots are missing important parts. There is a rule of evidence that if important context is missing, the messages may be excluded because they do not accurately tell the whole story.
So, back up your cell phones regularly to the cloud and to a computer, and keep your old cell phones when you transition to a newer model to preserve your evidence. Do not alter or delete messages from your message history, as a side-by-side comparision of the messages will cast doubt on the legitimacy of the evidence. And export your text messages into a good, readible format so that any reader can understand the important information and messages which were exchanged.
These concepts apply to other evidence. If you have the option to download PDF bank statements or take a screenshot from your phone, download the PDF. Even if the screenshot captured all the important information, it gives the other side license to complain about not having "the whole thing." Those complaints can cause unnecessary delay in you obtaining justice. It is worth the extra effort for you to obtain complete PDF records when you can.