Data Copyright / Use

DATA CANNOT BE COPYRIGHTED, EXCEPT....
Since data are not copyrightable, you will almost always be able to reuse the data itself. The two main exceptions to this are:

1. Those data protected by patent law (the inventor will hold the rights)
2. Data that are considered to be a trade secret (the employer will hold this copyright)

It's unlikely you'll have access to trade secret data, and if you do, the fact that it is in the public domain nullifies it's rights as a trade secret.

When Data DOES have an associated copyright...
Be aware that data can be copyrighted under specific conditions. Typically, there are three layers of data copyright:

1. Dataset Compilation Level
In this case, a copyright may be held by the compiler of data, such as an institution or repository might hold a copyright on data if the compilation includes enough original and creative arrangement.

2.  Organization Level 
If the organization of the data displays sufficient creative choices, it can be copyrighted

3. Item Level
If the presentation of an item, such as an image, a chart, a photograph, etc. shows clear creative choices, it will also be copyrightable

Despite these restrictions on re-using data presentations, the data themselves cannot be copyrighted and can be re-used.