Zack’s Time Zone Corner: How Time Zones Affect Data Processing

You know what daylight saving time changes mean: we’re back with another installment of Zack’s Time Zone Corner! Last time, we talked about basic time zone information and trivia. We’ll have more of that to come in future posts—and I promise a bit of that today if you make it through the article! For today, our focus will be on time zone considerations in eDiscovery since we are an eDiscovery company after all. The fun truly never stops! 

How To Pick a Time Zone for Data Processing

Whenever we’re processing data, we have to make a choice about what time zone to use and then keep it consistent for that matter. This is because date and time metadata is always stored in UTC (Coordinated Universal Time). While you often see a different time displayed on your computer, phone, or another electronic device, that’s because it’s converting the time from UTC to the time zone set on the device. The time zone chosen for processing will affect the native, text, metadata, and any images created of the native later in the case so make sure you’re choosing wisely! Here are some of the factors to consider before you pick a time zone for processing. 

Custodian Considerations 

You may think, “Well we collected the whole computer/phone/PalmPilot so can’t you just take the setting from the device?” In most instances, that would be possible, but it’s usually not what we’d recommend. 

Some custodians travel regularly, meaning the time zone settings on those devices could be updating automatically based on location. Additionally, there’s nothing to say that someone needs to have their time zone set based on their location. If a custodian lives in Mountain Time, but the majority of her colleagues/clients are in Eastern Time she might set her computer to Eastern Time to make scheduling easier. 

Additionally, most eDiscovery cases involve more than one custodian so if we were to rely on a single custodian’s time zone that can lead to confusion later, especially if other custodians aren’t in that time zone. It’s fairly common for cases to start with only one custodian and then more custodians are identified as the case proceeds. Those new custodians could be in different locations, and you want to be prepared for that.  

Opposing Counsel Considerations

Since we’re usually dealing with data from multiple parties, it’s best to coordinate time zone settings with the other side. 

Let’s say we have a case involving a dispute between ABC Corp. and Data Incorporated. Sally Docs from ABC Corp. and Donny Data from Data Incorporated were regular email correspondents, and those emails are relevant to the dispute. Reviewing productions from both sides will make a lot more sense if processed in the same time zone so you’re not looking at this:  

These appear to be the same email but since ABC Corp. used UTC and Data Incorporated used Eastern Time, they’re not only displaying different times but also different days. It’s best to have an agreement or protocol in place at the beginning of a case to avoid these situations. 

So What Should I Use!? 

Well that’s up to you! I’m just here to provide you with knowledge to form your own opinions. 

No, that doesn’t work? You want recommendations? Fine, we can do that.

For standard/traditional eDiscovery data types (email and eDocs from a computer, network, etc.), we generally recommend using UTC. As mentioned previously, we recommend coordinating with other parties so that all parties are using the same time zone. 

Of course, there are caveats which is why this is a general recommendation! If there is existing data which has already been processed in another time zone then it would be best to match that time zone to maintain consistency. 

For certain data types such as text messages and other mobile data, it may be best to use a local time zone depending on the processing method. With Contact’s MobileRev processing tool, we usually recommend that a single, local time zone is selected. This is because MobileRev generates records on a daily basis so you’d be more likely to separate specific conversations across different daily records if using a non-local time zone. 

Let’s say the custodians are all in Eastern Time, but the data is processed in UTC: all messages after 7:00 p.m. EST or 8:00 p.m. EDT will be in the next day’s record. Additionally, dates are always a key factor when we’re reviewing data, but for mobile data, the time is often more relevant than it may be with email. By using the local time zone, we can make sure it’s clear to reviewers that a text message occurred at 5:00 p.m. and not 10:00 p.m. That 5:00 p.m. “Coffee in the break room?” text message will likely appear much different to the reviewers than a 10:00 p.m. “Coffee in the break room?” text.  

What Can I Do to Change Time Zones? 

We always have different options to consider based on the specific situation. 

Most eDiscovery tools include a time zone offset feature that can change how an email is displayed within the platform. This can be helpful for review purposes, but it won’t change metadata fields, images, or the text itself.

For metadata fields, we can convert them to a different time zone. We’ll just want to be careful not to have mismatching values on the native/image/text and in the metadata. 

What to do about the natives themselves? We can produce a time zone field for clarity. We can also look at the specific scenario to determine if it would be feasible to reprocess the data or replace native files. 


Empowered with this information, you should be ready to make the best time zone decision for your case and specific data set in the future! Most of the time that will be UTC for email/eDocs or wherever the first few custodians are for your mobile data. 


As promised, your reward of time zone trivia! This is posting on St. Patrick’s Day so we wanted some Irish-themed time zone trivia. On St. Patrick’s Day, those of us in the USA are one time zone closer to Irish time than the majority of the year. This is because the USA starts daylight saving time before Europe, and St. Patrick’s Day falls in that in between time. 

P.S. – For everyone in Eastern Time, it’s EDT until November 7th!! (or use ET year-round!) 

Zack’s Time Zone Corner: DST ends, a new blog series begins

Daylight saving time has ended across the USA (teaser for later: it’s ended where it’s observed!). I’m sure everyone enjoyed the extra hour of sleep on Sunday. So what does that mean? It’s the perfect time to talk about time zones!

Why time zones? Well aside from the end of daylight saving time, a basic understanding of time zones has become even more important in 2020’s disparate, COVID-19 world. With more employees working remotely, there are additional time zone considerations. Many teams that were accustomed to working in an office together are now spread across the country. Maybe your D.C.-based team is now working from home in D.C., San Francisco, and Chicago. Maybe you’re planning to hire and realize you can expand your search geographically rather than limit it to a single metropolitan area. Here at Contact, we’ve hired four new team members in the past three months in three different time zones.

If you want to expand your business capabilities in our socially distant world, understanding time zones is crucial. “Let’s chat at 1:00 p.m.” doesn’t help if one person’s 1:00 p.m. is another person’s 11:00 a.m., and that’s not clarified. Technology has caught up to a point. Our phones and computers have time zones built into their clocks. Outlook and other email/calendar apps handle conversions for us. However, this also means it’s easy to get lazy about communicating time zones when we schedule things. I’m here to help make sure that doesn’t happen.

Key Things to Know!

So at the worst, time zones are a necessary evil that we need to understand in order to function in a world where so many people work remotely. At their best, they’re a fun, interesting Wikipedia rabbit hole to dive into for hours on end (No? Just me?). Either way, you’ve made it this far so it’s time to actually learn about the basics of time zones.


Coordinated Universal Time (UTC) is the standard used to synchronize times and time zones across the globe.

  • Time zones are communicated based on their relation to UTC so Eastern Standard Time (EST) is “UTC -5” because it’s five hours behind UTC.
  • UTC is along the prime meridian, or 0⁰ longitude.
  • While UTC and Greenwich Mean Time are often used interchangeably, Greenwich Mean Time has been measured differently at different points in history making it a less reliable standard compared to UTC.
  • How do we land on UTC as the abbreviation for Coordinated Universal Time? An international compromise between English and French speakers, of course! Didn’t I tell you this was fun?
  • UTC stays consistent year round. In places that observe Daylight Saving Time, we change the number that goes with their time zone. UTC never changes.

Daylight Saving Time

Daylight saving time (DST) is an additional component to your time zone understanding. Different countries, and sometimes different municipalities within a single country, make different decisions regarding the observance of daylight saving time. These observance decisions also change over time so there’s constantly new things to learn. That means the fun never stops!

  • Example DST observance difference #1:
  • Currently in the United States, DST begins on the second Sunday of March and ends on the first Sunday of November.
  • Currently in the UK and most of Europe, DST begins on the last Sunday in March and ends on the last Sunday in October.
  • This is why for most of the year, the United States Eastern time zone is five hours behind the UK, but for 3-4 weeks per year it’s only four hours behind.
  • Example DST observance difference #2:
  • Most of the continental United States observes DST. There are outliers such as Arizona which has not observed DST since 1967.
  • You might think “Arizona is in Mountain Time so it’s two hours behind Eastern Time!”, but you’d only be correct for four months of the year. The other eight months, Arizona is three hours behind because most of the country is observing DST.
  • Example DST change #1:
  • While there are changes that affect broader populations, Indiana is a particularly fun example. Time in Indiana has historically been such a mishmash that it has its own Wikipedia page!
  • Counties within the state are split between Eastern and Central time zones with counties changing numerous times over the years.
  • The same can be said for DST observance which has been inconsistent and has seen many changes. Since 2006, DST observance has been standardized so all counties now observe DST.

So Many Abbreviations

You’re right; there are lots of abbreviations. People often use the wrong abbreviations and miscommunicate their time zone. For example, who among us hasn’t used EST unwittingly in July when it’s actually EDT because of daylight saving time? Little did you know when doing that you were actually saying UTC -5, or the equivalent of CDT. After reading this, hopefully you’ll never do that again!

  • Suggestion #1: simplify your abbreviations! Few people want to type their time in relation to UTC even though it would be the most precise way of doing things. Abbreviations function as helpful shorthand. But in the US, you can easily say ET, CT, MT, or PT rather than EDT/EST, CDT/CST, etc. to communicate your time. You can save yourself from typing an extra letter and also prevent yourself from mixing up those abbreviations like saying EST during daylight saving time.
  • Suggestion #2: unsure about what abbreviation to use? Consult the internet or simply refer to the time based on a major city in your time zone. (Hint: the larger the city the better for this purpose.)

Reference Material

My personal favorite is You can find pages for individual cities and towns, time zone maps, and lots of fun articles. It’s a great one stop shop for all of your time and date essentials, including current and historical info about time zones, daylight saving time, and more.

Wikipedia is also a great source (as it often is) if you’d like additional info.

Do you have any other helpful reference material? Drop it in the comments!


There’s nothing to be scared about with time zones! With this background info, you can safely sit back and let your phones, computers, and apps handle the hard part for you. Now you can understand a little better what’s happening and maybe even regale people with your newfound passion for time zone knowledge.

This is just the start of our time zone education, so make sure you follow Contact Discovery Services so you never have to worry about missing a time zone lesson! (Okay, fine, we’ll post about other topics, too.)

P.S. – For everyone in Eastern Time, it’s EST until March!!