As you know, Bernie Sanders' campaign was involved in some recent hijinks involving improper access to campaign data from the Hillary Clinton campaign, after a buggy software patch applied by the contractor maintaining the Democratic Party's voter database, NGP VAN, inadvertently opened a data firewall. The Democratic National Committee (DNC) suspended the Sanders' campaign access to Democratic voter lists (a subscription that the campaign had paid for); Sanders responded by suing the DNC; after a brief negotiation, the DNC restored the Sanders campaign access [npr.org]; and Sanders apologized to Clinton [businessinsider.com] for the hack in Saturday night's debate. Clinton accepted the apology, and noted that most Americans don't care anyway.
Present company (possibly) excepted. Veteran Democratic campaign consultant David Atkins, who evidently has hands on experience using the software in question, pieced together what he thinks happened [washingtonmonthly.com]; including useful background on NGP VAN's software and its use by the Democratic party.
Atkins' bottom line:
As it turns out the ethical breach by Sanders operatives was massive, but the actual data discovery was limited. So it made sense and was fairly obvious that the DNC would quickly end up giving the campaign back its NGPVAN access—particularly since failing to do so would be a death sentence for the campaign and a gigantic black eye to the party.
Atkins also had some choice words for DNC chair Debbie Wasserman Schultz, agreeing with David Axelrod (Obama's former chief campaign strategist) that the DNC overreacted.
DNC CEO Amy Dacey blogged that the suspension of access to Sanders wasn't punitive [medium.com]:
This action was not taken to punish the Sanders campaign — it was necessary to ensure that the Sanders campaign took appropriate steps to resolve the issue and wasn’t unfairly using another campaign’s data.