Converting Invalid Local Time to UTC

$tz = [TimeZoneInfo]::FindSystemTimeZoneById('Eastern Standard Time')
$dt = (Get-Date '2013/3/10 2:30:00')

function CalculateTransitionTime([TimeZoneInfo+TransitionTime]$tt, [int]$year)
{
    if ($tt.IsFixedDateRule)
    {
        return New-Object DateTime $year, $tt.Month, $tt.Day, $tt.TimeOfDay.Hour, $tt.TimeOfDay.Minute, $tt.TimeOfDay.Second
    }
    else
    {
        $f = New-Object DateTime $year, $tt.Month, 1
        $dow = [int]$tt.DayOfWeek - [int]$f.DayOfWeek
        if ($dow -lt 0)
        {
            $dow += 7
        }
        $d = ($tt.Week - 1) * 7 + $dow + 1
        $result = New-Object DateTime $year, $tt.Month, $d, $tt.TimeOfDay.Hour, $tt.TimeOfDay.Minute, $tt.TimeOfDay.Second
        if ($tt.Week -eq 5 -and $result.Month -ne $tt.Month)
        {
            # week 5 means 'last week of the month'
            return $result.AddDays(-7)
        }
        else
        {
            return $result
        }
    }
}

function ToUtc([DateTime]$dt, [TimeZoneInfo]$tz)
{
    if (-not $tz.IsInvalidTime($dt))
    {
        return [TimeZoneInfo]::ConvertTimeToUtc($dt, $tz)
    }

    $d = $dt.Date
    foreach ($ar in $tz.GetAdjustmentRules())
    {
        if ($d -lt $ar.DateStart -or $ar.DateEnd -lt $d)
        {
            continue
        }

        $transitionTime = (CalculateTransitionTime $ar.DaylightTransitionStart $d.Year)
        if ($transitionTime -le $dt -and $dt -lt ($transitionTime + $ar.DaylightDelta))
        {
            return [TimeZoneInfo]::ConvertTimeToUtc($transitionTime + $ar.DaylightDelta, $tz)
        }

        $transitionTime
    }
}