Courts almost always issue a temporary Order of Protection (restraining order) at the arraignment. A 'full stay-away' order means you cannot contact the protected party at all, even if you live together. Violating this is a separate crime.

In civil cases, the standard is usually a 'preponderance of the evidence' (more likely than not), which is lower than the criminal standard of 'beyond a reasonable doubt.'

In federal investigations, wiretaps are common. However, they require a court order based on probable cause. If you suspect you are being investigated, assume your communications are not secure.