If you've been accused of driving under the influence (DUI), a lot of the argument depends on blood test results, breathalyzer tests, and police statements. If there is any doubt about the tests, there's a doubt about the entire process, and if there's doubt, you just need to start stacking up to support for your innocence. Don't talk to the police unless instructed to by an attorney, and consider a few of these evidence-gathering points to support your side of the argument.
A Note About Tampering
Before grabbing, adjusting, or even thinking about editing, keep in mind that tampering could invalidate your case or be considered an obstruction of justice. Destroying evidence is a major problem, but some people attempt techniques that may seem helpful without considering the consequences.
You may find a picture or video of evidence and feel the need to highlight the proof of your innocence. This could include editing a video down to the relevant clip(s) of time that show the event, or drawing circles around key areas.
This creates an easy opportunity for an opposing lawyer to claim that you edited the evidence to be in your favor. Even if that's not plausible by industry standards, a courtroom may take the safer approach by considering any editing to be potentially malicious.
Contact your attorney before doing anything. At the most, you should make your own copy and turn the original evidence over to your attorney, who can then report the evidence to authorities. Once the original evidence is confirmed to be relevant and part of the case, you can then work on highlighting what you think is relevant within your own copy.
What Digital Evidence Could Save You?
In DUI situations, there are often arguments over how the driver was driving--or whether the driver was driving at all. There are situations where a police officer may stop you at a bar or club just because you're sitting in the driver's seat with your keys, even when you didn't intend on driving.
You will need to prove that you either weren't driving at all or that your driving did not seem impaired. This means tracking down surveillance video from local businesses and other buildings or getting video evidence from a bystander.
To receive that evidence, have a few backup storage options on hand. Some security cameras may still use CDs or DVDs, while many cameras and smartphones will use SD (secure digital) cards. Don't just assume that a witness can afford a data plan to just send you the video wirelessly, and don't assume that every area will have free Wi-Fi when you're close to the evidence you need.
Contact a DUI attorney to discuss your situation, and to get advice on your evidence.