If I witnessed a felony, do I have an obligation to report it to the authority? If I did not report, and the authority later found out I was one of the witness, would I be charged with obstruction of justice, especially if I was the only witness and/or I was fully aware of what was going on but chose not to report? Thanks.
That completely depends on the state for typical felonies such as murder, assault, etc (and this is not always synonymous with the so called “good Samaritan” laws. Which state are you talking about?
In most jurisdictions (and federal comes to mind) failure to report a felony technically makes you an accessory. (of course the ability to charge you with a crime doesn’t mean you’d be charged with it let alone convicted).